Translate mathjax-helper to coffescript

For future development within atom, it will be far easier to maintain
coffescript over javascript.
Remove MathMenu and MathZoom MathJax functionality
Move renderLaTex conditioning to mathjax-helper
Add postprocessor to fix inline eq md processing

Fixes issue where inline equations were being processed for markdown
syntax. The technique wraps them in code blocks to shield them from most
of the markdown processing.