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.
* Adds session_detail page
* Adds session chairing information to the schedule grid
* Adds session_list.html
* Nicer volunteer text
Conflicts:
pinaxcon/templates/symposion/schedule/_grid.html
Conflict and migration performed by Sachi King <nakato@nakato.io>
Emoji changed, lca2017_tags to lca2018_tags, remove needless dependency
on django-user-account, use request instead like the remainder of the
calls n the template do anyways.
Remove blocktrans from a number of texts as they break {{ templating }}
and we don't translate anyways.
Modified-by: Sachi King <nakato@nakato.io>
