feature(client): Flash messages

issue #891
fix(build): Use the custom version of Modernizr in prod, not the full version.

fixes #949
refactor(test): Less auth-server logging for travis tests!

Only display errors.
chore(l10n): fix supported locales script to print correct missing strings
Merge pull request #984 from mozilla/issue-949-future-of-the-past

fix(build): Use the custom version of Modernizr in prod, not the full version.
Merge pull request #924 from mozilla/issue-891-flash-message

feature(client): Flash messages
Merge pull request #998 from mozilla/fix-supported-locales

chore(l10n): fix supported locales script to print correct missing strin...
Merge pull request #1004 from mozilla/less-auth-server-logging

refactor(test): Less auth-server logging for travis tests!
feature(client): Add Firefox for Android marketing on the confirmation screen.

fixes #900
cleanup(css): Extract inline color values to _variables.scss

* cleanup for @pdehaan's comments in #1003

fixes #1009