[fix bug 1060614] mozilla wordmark on homepage does not work in IE 6 & 7
[fix bug 1049042] Update Firefox OS FAQ page
[fix bug 1067281] Remove duplicate CSS files from bedrock pages

- /mission/
- /about/powered-by/
- /firefox/channel/
- /firefox/os/devices/
- /about/manifesto/
- /plugincheck/
- /privacy/ base template
- tabzilla.less imported lib.less twice
Merge pull request #2257 from alexgibson/1060614-mozilla-wordmark-ie7

[fix bug 1060614] mozilla wordmark on homepage does not work in IE 6 & 7
Fix bug 1066629: Add contribute.json
Merge pull request #2268 from pmclanahan/add-contribute-json

Fix bug 1066629: Add contribute.json
Merge pull request #2273 from alexgibson/bug-1049042-update-firefox-os-faq

[fix bug 1049042] Update Firefox OS FAQ page
Merge pull request #2278 from alexgibson/bug-1067281-remove-duplicate-css-files-templates

[fix bug 1067281] Remove duplicate CSS files from bedrock pages