Fixed issue with " ," rendered instead of ", "
Merge pull request #18 from woudshoo/comma-space-issue

Fixed issue with " ," rendered instead of ", "
*injections* was never set to nil, so kept growing indefinetely
Merge pull request #19 from woudshoo/injections-growth

*injections* was never set to nil, so kept growing indefinitely
Added options to MathJax plugin, also updated documentation
Added mathjax-config argument.
Also allow for nil argument to mathjax-config
Merge pull request #20 from woudshoo/mathjax-improvements

Mathjax improvements
Mathjax plugin cleanups.