Wafer

Notable features
* We now also support Django 2.1 & 2.2
* Minimal CSS styling for the schedule, so it looks better by default
* Pin dependencies so installation doesn't break with python 2.

All relatively minor changes. 0.7.7 probably should have been 0.8.0, but better late than never.

Minor:
1. Change the UI for track and type selection, in the talk submission form. This allows longer descriptions to be visible, without breaking usability.
1. UI Tweaks around profiles.
1. 403 requests to user profiles (without accepted talks) when WAFER_PUBLIC_ATTENDEE_LIST=False.
1. Include iCal schedule in static export.

Translations:
1. Complete pt_BR.
1. `.mo` files are shipped in the release.

Dependencies:
1. *Finally* with a dependency stack supporting Django 2.0 (a little late). Expecting 2.2 soon.

* Fix the schedule editor to work better on non-chrome browsers
* Add a close button to newly added items in the schedule editor
* Improve the handling of sponsors in the menu
* Display the range of review scores on the review widget

* Improve schedule editor
* Improve schedule validation error reporting
* Fix page editing live markup preview
* Compatibility with djrf >= 3.8.0
* New settings:
* WAFER_VIDEO_LICENSE
* WAFER_VIDEO_LICENSE_URL