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 1064773] Newsletter form thank you message is always visible on IE 6 & 7
Add Nicaragua to ZTE Open 2 country list. Bug 1064566.
Add new provider links to FxOS devices. Bug 1065332.

- Alcatel One Touch Fire C in Macedonia (T-Mobile) and
  Greece (Cosmote).
- Alcatel One Touch Fire E in Poland (T-Mobile).
Merge pull request #2266 from jpetto/bug-1064566-fxos-nicaragua-avail

Add Nicaragua/ZTE Open 2 avail to FxOS pages. Bug 1064566.
Merge pull request #2267 from jpetto/bug-1065332-fxos-add-provider-links

Add new provider links to FxOS devices. Bug 1065332.
Merge pull request #2265 from alexgibson/bug-1064773-newsletter-thank-you-message

[fix bug 1064773] Newsletter form thank you message is always visible on IE 6 & 7
Fix bug 1065744 - update MoCo steering committee
Fix bug 1061228: Fix locale redirect exemption in page() helper.
Merge pull request #2270 from pmclanahan/fix-credits-faq-1061228

Fix bug 1061228: Fix locale redirect exemption in page() helper.
Redesign Firefox Sync page for Bug 1046251
- Conditional contents depending on browser type/version
- New content/design only applies to en-US until other locales opt-in
Merge pull request #2263 from sgarrity/bug-1046251-sync-updates

Redesign Firefox Sync page for Bug 1046251
Bug 1061228: Fix broken credits/faq.
Merge pull request #2272 from pmclanahan/fix-broken-credits-faq-1061228

Bug 1061228: Fix broken credits/faq.
[fix bug 1049042] Update Firefox OS FAQ page
[no bug] Add <main> element to CSS reset
[fix bug 1066661] Firefox /new page loads template-resp.less twice
Improve mozilla-accordion.js. Bug 1055830.

- Add collapse/expand callbacks.
- Add ability to programmatically create/destroy accordions.
- Add mozilla-accordion.js tests.
- Add standard GA callback JS for existing accordion pages.
- Standardize mozilla-pager.js create param to jQuery obj.
- Update accordion & pager docs.