Fix bug 1104864 - Correctly handle "other" email.

This fixes an actual broken piece of the custom email address signup scheme.
Fix Bug 1104125: Integrate 10th anniversary styles

Integrated 10th anniversary styles and remove the 10th anniversary separate style sheet and waffle.
Merge pull request #2935 from stephaniehobson/BUG-1104125-demos-integrate

Fix Bug 1104125: Integrate 10th anniversary styles
Merge pull request #2945 from jezdez/bug1104864

Fix bug 1104864 - Correctly handle "other" email.
Merge branch 'master' of https://www.github.com/mozilla/kuma
Synced with master mozilla/kuma