Bug 849426: Port /about/history.html to bedrock

- new pages created on wiki with old content of some pages:
  - www.mozilla.org/about/bookmarks.html ->
           https://wiki.mozilla.org/Historical_Documents
  - www.mozilla.org/about/timeline.html ->
           https://wiki.mozilla.org/Timeline
- new /about/history/ page on bedrock with existing content from
  old /about/history.html, and links to new wiki pages
- added rewrite rules so new history page is served from bedrock and old
  bookmarks and timeline pages redirect to the new wiki pages
- used about-base.html template for history page
- Added some more information to the install doc about getting the PHP
  and Bedrock sides of the site running locally with Apache.
- Make about.less import about-base.less and then add mosaic to it,
  so it's clear that the only difference is the mosaic.