Commit basic mathjax code before going to bed.

Todo:
1) Refactor youtube code
2) Refactor edit to app/views/layouts/application.html.erb and enter
the mathjax javascript load logic into another file.
3) Why does mathjax not work well in the presence of the formatter?
temporary commit: moving from home to work
Mathjax support factored out and placed into red_formatter.rb
changes to Gemfile to remove the auto_html gem. Youtube url embed works on RedPlus
reverted forem files back to their original state. Youtube embedding done via RedCarpet and RedPlus
Merge branch 'dev.mathjax' into dev

Completely done with refactoring youtube code into the RedPlus formatter
Introduced the mathjax renderer for latex.

Bug: still not getting mathjax to render on firefox 24 upon first access to page. requires reloads.