Make subject line of contribute email for end-users localizable.

Keep the existing filterable subject lines for Mozilla contacts.
Fixes 854992
Bug 912055: Update basket-client
Bug 912055: Support invalid email errors from basket.
Fix Bug 911672 - Mails sent to contribute-form@mozilla.org are bouncing
Fix Bug 933311 - Add a /humans.txt url to bedrock

#1553 added the file. This adds a RewriteRule to enable it.
Fix Bug 926243 - Adjust font size for localized Firefox OS promo on Tabzilla
Fix Bug 966409 - Use the real Firefox wordmark on the home page
Merge pull request #1680 from kyoshino/bug-933311-humans-txt

Fix Bug 933311 - Add a /humans.txt url to bedrock
Fix bug 964878 - Update 'Get a Phone' CTA for Chile
Merge pull request #37 from mozilla/bug-964878-update-cta-for-chile

Fix bug 964878 - Update 'Get a Phone' CTA for Chile
[bug 972454] Add Fox Den register link to MWC teaser page
Merge pull request #1710 from alexgibson/bug-972454-add-fox-den-register-link-mwc-teaser-page

[bug 972454] Add Fox Den register link to MWC teaser page
Merge branch 'master' of github.com:mozilla/bedrock
Add register link to MWC schedule modal. Bug 969102.
[bug 964878] Add Chile to provider list on Firefox OS FAQ page
Merge pull request #1712 from jpetto/bug-969102-add-register-link-to-mwc-schedule

Add register link to MWC schedule modal. Bug 969102.
Add site-wide MWC badge. Bug 958287.
[bug 974467] Update mwc fox den calendar wednesday feb 19
Merge pull request #1715 from alexgibson/bug-974467-update-mwc-fox-den-calendar

[bug 974467] Update mwc fox den calendar wednesday feb 19
[bug 974467] update mwc fox den calendar remove desc