Apply `futurize --stage-2` Python 2/3 compatibility transformations.

These changes specifically require the use of the "future" library.

Add unique constraint to Staff.username.

Previously had some duplicates for "pono" which were causing
MultipleObjectsReturned errors. A username is generally considered to be unique.

Continuing saga of the sizing chart problems for original shirts

Gildan removed the sizing chart entirely from their website again
after yet another redesign. Originally, we deep-linked into files in
their CDN for the charts, but it appears that in 5c72071 that I
introduced cut-and-paste error on the sizing charts. I cannot find
the original links, but finally I simply decided we'd mirror the
files in our CDN, which is where these now link to.

I suspect that I didn't do this to start for worrying about copyright
infringement, but upon second thought, I think it's very reasonably
fair use for us to distribute these images. We bought a lot of
t-shirts from Gildan and just trying to sell through.

progress bar: Remove display-table vertical align workaround.

Was causing some display glitches on some browsers. Using nested flexbox instead.

progress bar: Drop JS, make mobile friendly, match design to new site.

The existing jQuery UI-based fundraising progress bar used a float layout,
making it hard to adapt for mobile use. Given that there is not interactivity,
I've dropped all the JS and switched to a flexbox layout. This works well
because the bar will stretch to fit the text rather than always maintaining its scale.

Sidebar should disappear on small screens.

We've had a report that the sidebars are very distracting,
particularly for the blogs, on smaller screens. This change to the
CSS will cause sidebars to disappear on smaller screens.

Format like previous with the <p> solution

<ul> is the right HTML way to format these, but they are all too
close. Get it to look more like it did with <p>'s with CSS.

Use typical way of putting the category in a block.

Django is so frustrating as it's never clear about how things trickle
up and down through templates, so move the category to the top like
the others.

Format like previous with the <p> solution

<ul> is the right HTML way to format these, but they are all too
close. Get it to look more like it did with <p>'s with CSS.

Use typical way of putting the category in a block.

Django is so frustrating as it's never clear about how things trickle
up and down through templates, so move the category to the top like
the others.

Additional fixes for menu items related to news and press

A few additional places where the news and press pages were not
properly menu integrated. This fixes various inconsistencies and
missing category and submenu markings in menus.

Fix minimal start of ourcoverage.html and correct various problems

ourcoverage.html was a reasonable minimal start but not really ready
for production. Make changes necessary to put this into production,
as follows:

* Rename ourcoverage.html to vizio-coverage.html. This is just
Vizio coverage for now.

* Order articles by most in-depth/interesting. Verified this
ordering by consensus with Conservancy staff.

* mailto: link for press coverage on the main inthenews page, but
don't use that on Vizio page; it's unlikely we'll miss any of the
Vizio coverage.

* use &mdash; instead of -

* put quotes around article titles.

* Add missing PR Web article

* Switch from <p>'s to <li>'s in vizio-coverage.html

* Fix menu issues. 09a4b02 outlined the issues regarding how to
add items to menu; it does require a CSS change as explained
therein; merely using the right `base_` is not enough

* Improve menu integration. Per PR people's recommendation, the
Vizio stuff that also goes in other areas needs to be placed in
multiple menus.

fixup /press from Hannahs notes

a few s/supporters/sustainers/
add link to inthenews
update news and press menu

Vizio — For compliance only, note resources are for Vizio

The Resources for Journalists are only related to Vizio, so make that
read that way on compliance pages that *are not* Vizio pages.

Repair menu highlighting, both for main menu and submenus

During the recent improvements made on the website, the menus and
submenu highlighting for selected menus fell into disarray.
Correction requires changes to the CSS and templates both, because
Django doesn't really have a convenient way to set variables in
templates to use to solve this.

There are still a few submenu items highlighting not working even
after this commit. More work needs to be done.

Copyleft Compliance — Vizio — put two links in Learn about it

This unreverts 613674c07189b4a973610d15c8451ae2f4d7bb59

Copyleft Compliance — Vizio — put two links in Learn about it

This unreverts 613674c07189b4a973610d15c8451ae2f4d7bb59