cleans up home page header design, adds social sharing to header, adds tos, privacy policy, honor code, help and copyright pages, add liks to those pages in footer, finished contact page

adds pressrelease page, breaks about content into seperate pages, imporvoves some visual elements of about and jobs pages

Allow module html to link to global static files as well as course static files

Fixed the errors that were breaking tests from unused simplewiki files and a half-migrated certificates module.

Only munge /static/ urls in module html to point to course static files if they don't exist in the global static locations

The path user by url is based on the output css file, which ends up in static/sass, so only use ../, rather than ../../, to reference images

Don't crash the system if you can't parse an xml file while loading a definition for a module descriptor

updating activation mail, adding Gemfile.lock to gitignore

Multicourse wiki

Utf8 migration merge

CMS import backwards compatibility

 - edx4edx and 8.01x course repo errors fixed and verified
 - moving forward, it would be nice if the LMS+CMS xml import failed more gracefully when encountering errors in the xml files, when in debug or authoring mode.  For example, an inadvertent xml error in one problem (eg created by a mistake in an import tool used in the CMS) should not bring down the whole LMS. Ditto if one problem gets deleted from the mongodb or filesystem.

Allow importing of courses that don't have the expected path/filename structure for problems and html

This cleans up remaining issues w/ https://github.com/MITx/mitx/pull/155