Fix bug 850431 15th Anniversary slide show on /contribute

commit from pascalc: use 15years.lang as an extra lang file for the campaign. Split a sentence in two l10n blocks because that's how I gave it to localizers

commit from jpetto: Added stub for GA tracking slide views.

Will track 3 separate actions - auto, click, keydown.

commit from jpetto: Added GA tracking code.

commit from pascalc: Bug 854232 - [zh-CN] 15 Years campaign, activate the locale

commit from craigcook: Fix validation errors in contribute form

"true" isn't a valid value for the required attribute (it's a boolean attribute)

rows and cols attributes require a positive integer value; the empty string isn't valid.
PNG optimize
0.x > .x / 0deg > 0
Merge pull request #724 from ethertank/css

Unification of some formats and image data compression
Add transaction names to page calls for newrelic differentiation.
Update marks for zh-TW and zh-CN
Merge remote-tracking branch 'craigcook/bug-850431-15-year-anniversary'

Conflicts:
	apps/mozorg/templates/mozorg/contribute.html
	apps/mozorg/views.py
Merge remote-tracking branch 'craigcook/bug-850431-15-year-anniversary'
Re-enable default scrolling during swipe
Fix bug 855103 - 15th anniversary home page promo
FxOS style guide additions. Bug 854998.

partners/community pages added to fxos styleguide. Bug 854998.

FxOS style guide additions. Bug 854998.

Added community and partners pages to Firefox OS
styleguide.
Merge pull request #725 from jpetto/fxos-style-guide

FxOS style guide - add partners & community pages
Update mozilla-based page. Bugs 854561, 830914, 833055.

- Change /projects/mozilla-based/ to /about/mozilla-based/.

- Redirect /projects/mozilla-based.html to /about/mozilla-based/.

- Update product links.

Localization & URL rewrite fixes.

Wrapped string in l10n blocks. Updated rewrite rule to
handle trailing slash..

Added missing localization.
Merge pull request #710 from jpetto/mozilla-based-cleanup

Update mozilla-based page. Bugs 854561, 830914, 833055.
Merge pull request #726 from pmclanahan/rename-page-helper-view-newrelic

Add transaction names to page calls for newrelic differentiation.
Merge pull request #728 from craigcook/bug-855103-moz15-home-promo

Fix bug 855103 - 15th anniversary home page promo
Bug 851727 -Responsify powered-by page

Migrate /projects/powered-by.html to bedrock. Bug 851727.

UI cleanup. URL redirects added (review needed).

Built on @retornam's initial branch.

Updated img alt attr, fixed phone view.

Updated URL rewrites (thanks @pmclanahan).

Updated URLs/rewrites to replace /projects/ with /about/.
Bug 835506: Fix Download Tab bugs

Delay download so window.location doesn't block rendering of background images. Restore "click here" fallback download link's URL in scene 2.
Merge pull request #702 from jpetto/Bug851727

Migrate /projects/powered-by.html to bedrock
Merge pull request #730 from Nobox/master

Bug 835506: Fix Download Tab bugs