Fix bug 860875: Offer localized build from query param.

Fix bug 860819: Wrap strings for l10n.
Bug 857842: Force installer-help page to offer full installer.
Merge pull request #805 from pmclanahan/use-lang-from-stub-installer

Fix bug 860875: Offer localized build from query param.
Bug 859537 Russian contribute page
Merge pull request #829 from pascalchevrel/bug-859537-russian-contribute-page

Bug 859537 Add russian contribute page
Revert "[bug 859564] Add /b/ redirect for /contribute/universityambassadors/"

Reverting because this page is not ready.

This reverts commit be67aa484eb358b4e195bb8c12d9ecf6e862d0e7.
Bug 867658 - Adding T-Shirt promo banner to homepage