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/.
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
Add opengraph metadata for moz15, increase slideshow delay
Merge pull request #731 from craigcook/bug-850431-15-year-anniversary

[moz15] Add opengraph metadata, increase slideshow delay
Bug 852225 - override italics for zh-CN and zh-TW

Needed a specificity boost.
Merge pull request #732 from craigcook/bug-850431-15-year-anniversary

Bug 852225 - override italics for zh-CN and zh-TW
l10n: add an email address (temporary) for German contribute page.

This will allow them to participate in 15 years anniversary campaign.
This address is a temporary one that we will use while they have a
proper mailing list set up in Bug 856876.
mobile min spec bump
Merge pull request #734 from AaronMT/membump

Mobile min spec adjustment (platforms.html)
Bug 857085: German, Contribute page, use moz15-mark-de.png instead of  moz15-mark-en.png
Merge pull request #736 from pascalchevrel/bug-857085-german-contribute-page-fix-header

Bug 857085: German, Contribute page, use moz15-mark-de.png
Bug 856464 Removing pancake from products page because it is no longer an active project:
Merge pull request #727 from retornam/bug856464

Bug 856464 Removing pancake from products page because it is no longer a...
Bug 835506: Fix error 500 in Download Tab

In Python 2.6, curly brace placeholders used in the str.format() must have an identifier. See http://stackoverflow.com/questions/10054122/valueerror-zero-length-field-name-in-format-python