Fix venueless token creation

Do not generate token or checkin if user does not have a ticket.
Clear existing token if user no longer has a ticket.

Fix dashboard for non registered users

Do not show launch conference section if user has not purchased a ticket.

Add Venueless integration to Regidesk

Create Venueless login token as part of checkin to allow attendee to
join an online event from the dashboard.

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.

Raffle improvements

Add flag to enable/disable raffle display on dashboard.
Add link from raffle winner to attendee profile.
Add URL for single raffle and base raffle path.

Registrasion updates

Show applied vouchers on attendee registration admin page.
Add head title and page title to more areas.
Update the dashboard to show warning for empty categories and have
button to open voucher page.
Fix exception on attendee page when user does not have attendee object.

Improved dashboard styling

Display proposals in rows and columns, instead of all on one row.
Fix spacing for sections on the page.
Improve small screen display of page.

Finalise registration

Add shirt types and sizes. Improve messaging about discounts.
Restyle ticket wizard and product category screens. Enable page titles
and messages. Update dashboard to hide raffle.
Enable inventory population for dev container.

Improve proposal/review styling

Use correct block for page titles. Fix element styles to be consistent
across site. Use fluid layout for review to enable sidebar.

Switch to LCA2020

Remove LCA2018 and LCA2019 styles and content.
Add base LCA2020 styling and update references to year.