Fix Bug 975020 - Translation Bar and non-locale redirects don't work as expected in some cases; use the user's accept language list to fix it
[fix bug 977391] Fix GA tracking in form signup on /contribute
bug 977391 - add video engagement tracking

Track pause/play events on the video sequence.
Merge pull request #2054 from craigcook/bug-977391-video-tracking

bug 977391 - add video engagement tracking
Merge pull request #2035 from mozilla/bug-977391-fix-ga-tracking-contribute-page

[fix bug 977391] Fix GA tracking in form signup on /contribute
Merge pull request #1771 from kyoshino/bug-975020-user-lang

Fix Bug 975020 - Translation Bar and non-locale redirects don't work as expected in some cases; use the user's accept language list to fix it