Update to Django 2.2

Upgrade site and modules to Django 2.2. Remove and replace obsolete
functionality with current equivalents. Update requirements to latest
versions where possible. Remove unused dependencies.

Remove AceEditor

I cannot find the benifit to this over the base editor.

Tabs work, but that's pretty minimal. And tabs don't work on GitLab or
GitHub, so I don't feel not having that is substantual to functionality.

Use a selectbox for of_legal_age

To me, this registeres to a user as a required field better than a
radio-button.

As well, we now signal it as "required = True"

Remove 500 patch. 1.7.0 upgrade.

While 1.7.0 exhibits a similar issue, we would need to re-verify and
re-patch this library with a new 1.7.0 monkeypatch.

This is ultimately only an annoyance. It only occours when we've
already 500'd, and this just means we get a second 500. As such it's
not critical.

Remove dj-user-accounts

That's a nice macro, but we don't need it.
dj-user-accounts stands in the way of using more generic AUTN_METHODS

Use outbound mail provider for admin BCC

We can use our outbound provider to BCC any required administive
retention that is required.

Mass style-check update

Seems okay.

Adds registration to the website (#69)

* Updates settings and requirements

* First pass at attendee profile

* Imports the registration templates; defines attendee profile models etc.

* First pass at themeing the registration form.

* First page of the registration form: done!

* Makes form validation nicer

* Adds populate_inventory

* Improves the additional items page

* Allows for rendering of formsets.

* Adds support for formset extending.

* Removes formset delete buttons

* Review page is LCA-ified

* Fixes some formset behaviour

* Fixes urls.py

* LCA-ifies product_category.html

* Invoices

* Credit card payments

* s/register/tickets/

* Show registration features only whilst products are available (think about this better, later)

* Updates the attendee profile form page

* Form tidy-up

* Makes it so that address info is copied from attendee profile to the address details are autofilled in Stripe.

* Adds feature to offer Australians a dropdown list of states rather than free text.

* Allow toggling of void invoices.

* Adds backgrounds to the headers in the registration process

* Improves the review page

* Adds “Linux Australia” to invoice details.

* Do not show balance due on void/refunded invoices.

* More thumbing

* Adds a link back to reports on each report.

* Tokenisation language.

* Another bug in credit card processing.

* Adds stripe refunds to options

* Removes spurious dashboard button.

* Tidies up the presentation of discounts.

* Tidies up presentation of voucher form.

* Fixes sponsor logo appearance with adblock.

* Front page tweaks

* Lets us specify alternative URLs in homepage panels

* more

* Updates discount amounts.

* More website fixes

* Changes language on pay invoice button

* Adds contact details to the invoice template.

* Updates the currency message in the invoice template.

* Explicitly includes e-mail address, because theme_contact_email doesn’t propagate

* Changes payment text.

* s/registration/selections/

* Removes final face palm

* Fixes lack of speaker dinner tickets for actual presenters.

* Adjusts wording in invoice e-mails

* Invoice wording.

* (FIX)

* Fixes margins on lists and tables

* Improvements arising from those CSS fixes.

* Changes description tags.

Makes sure BCC is provided to *every* e-mail. (#65)

* Replaces the monkey patch on send_mail, and replaces it with a monkey patch on EmailMessage’s constructor.

* Removes spurious print statements.

* Minimum viable changes to get schedule to display (#64)

* All migrations are now in this tree

* Replaces the monkey patch on send_mail, and replaces it with a monkey patch on EmailMessage’s constructor.

* Removes spurious print statements.

Fixes for 20160718 (#54)

* Simple form input fields now use TakeFlight styling

* Styles the form widgets as per the styles in our CSS

* Styling of TextArea now matches the remaining input types

* Adds is_last modifier to navigation dropdown

* Adds admin for talk, tutorial, and miniconf proposals

* Adds an RSS feed

* Adds a link to the RSS page

* Unbreaks the old news index page

* Adds never_cache to the login page, removes the never cache middleware from the settings

Assorted fixes (#47)

* Invokes the site tree fix from previous fixes.

* Adds a disclaimer noting that previous years’ accounts have not been carried over.

Fixes #43

* Adds proposal type to the proposal summary page.

Fixes #40

* Adds travel/accommodation assistance to the proposals page, but makes it only visible to speakers in the proposal, or review managers.

Fixes #41.
Fixes #42.

* Reduces a lot of the whitespace in the header and footer.

Fixes #44

* Proposals review page now shows information for every speaker on a proposal.

Fixes #45

* Makes sure that non_field_errors are displayed by forms.

Fixes #37

Fixes django-sitetree’s breaking of 500 reporting. (#39)

Friday fixes (#36)

* Monkey-patches a version of send_email that allows BCCs into the django accounts signup process. wtf, etc.

* Adds alt-text to site header

* Favicon.

Tuesday & Wednesday work (#30)

* Fixes an incorrect link in dashboard

* Disables the symposion sponsors app

* Adds redirect links for login/logout; adds THEME_CONTACT_EMAIL value

* Re-adds colophon/copyright message.

* Adds AceMarkdownEditor widget

* Tidies up the generated HTML

* Tidies up form snippet behaviour

* Proposals forms now use the markdown editor

* Monkey patches the markdown editor into the speaker form.

* Adds missing field to proposal details

* Fixes #10 — adds a link to random unreviewed proposals

* Minor tweaks