bug 932108 - Tabzilla formatting issues

Repositioned the `Search` placeholder by adjusting the line-height. It was affected by css from the body.
Replace mixins.less & variables.less w/lib.less. Bug 1057419.

- Delete mixins.less & variables.less.
[fix bug 1060614] mozilla wordmark on homepage does not work in IE 6 & 7
[fix bug 1049042] Update Firefox OS FAQ page
[fix bug 1066661] Firefox /new page loads template-resp.less twice
Bug 1065744 - update steering committee date
Merge pull request #2275 from alexgibson/bug-1066661-firefox-loads-css-twice

[fix bug 1066661] Firefox /new page loads template-resp.less twice
Merge pull request #2276 from craigcook/bug-1065744-update-steering-committee

Bug 1065744 - update steering committee date
Bug 1065744 - add Andreas Gal to steering committee
Merge pull request #2277 from craigcook/bug-1065744-update-steering-committee

Bug 1065744 - add Andreas Gal to steering committee
Merge pull request #2249 from rubenvereecken/new-issue-932108

bug 932108 - Tabzilla formatting issues
[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
Add GoFox F15 phone to FxOS devices page. Bug 1065651.
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
Merge pull request #50 from mozilla/bug-1065651-fxos-gofoxf15-device

Add GoFox F15 phone to FxOS devices page. Bug 1065651.
Revert "Add GoFox F15 phone to FxOS devices page. Bug 1065651."

We will hold this until further notice.

This reverts commit 4a79bdd7fd3f03c7beef98beb717c7978a6f3969.