Bug 1082853: Configure CSSLint and validate MDN CSS

Made a more decerning vendorize mixin with lookup tables for values.
Made a mixin for creating rgba fallbacks.
Remove table.activity which was presumably added back in during a merge somewhere).
Validate CSS, mostly working with outlines.
bug 916229 - proposing a patch to fix the bug
Merge remote-tracking branch 'mozilla/master' into bug916229
bug 916229 - formatting sql queries and adding {% trans %} block
bug 916229 - moving the querying into Celery task
BUG 1087015: Demos - menu

Fix "browse by technology" menu being open by default.
Bug 1087015: Demo Stuido - gallery page

- Gallery page now stacks
- Replaced JS that created "card" effect on hover with pure CSS
- Revived background image on not-the-landing-page
- Restricted button styles to act within main content
- Added clearing to all columns when they collapse.
Merge pull request #2853 from stephaniehobson/BUG-1087015-demos-gallery

Bug 1087015: Demo Stuido - gallery page
Merge pull request #2855 from stephaniehobson/BUG-1087015-demo-menu

BUG 1087015: Demos - menu
bug 1084110 - Upgrade stylus on VMs
fix bug 1088403 - add bn-IN locale
Merge pull request #2856 from darkwing/upgrade-stylus-again-1084110

bug 1084110 - Upgrade stylus on VMs
bug 1072493 - Adding more homepage tests, navigation submenu validator, search box expanding, footer dropdown language widget changing
Merge pull request #2847 from darkwing/more-tests

bug 1072493 - Adding more homepage tests, navigation submenu validator, search box expanding, footer dropdown language widget changing
bug 1072493 - Shorten basic visibility tests, remove sleep() calls when possible
fix bug 1087527 - use the SessionAwareClient in more tests

This seems to have been a leftover from 5743ed2059ccd4dc02ed7ccb789d2f637c2dfc2f.
fix bug 1072380 - make sure we raise validation error at the right spot of the call chain.

The problem was that the validation error was raised at a stage where it didn't trigger a re-rendering of the page.
This also contains some refactoring of the newsletter feature to encapsulate it in the NewsletterForm.
bug 1072493 - Add shortcut method for global property checks
bug 1072493 - Make the login widget open functionality a util so it can be used often.
Merge pull request #2858 from darkwing/more-test-updates

bug 1072493 - Shorten basic visibility tests, remove sleep() calls when possible