Separating MediaWiki specific files from MathJax module

This commit separates the files wiki2jax.js and texvc.js from the
MathJax modules. This allows for MathJax updates without affecting
MediaWiki files. It also defines the MediaWiki path configuration,
although this will really only be usable in MathJax 2.4. Finally,
it fixes jshint errors in texvc.js and wiki2jax.js

Moved texvc.js and wiki2jax.js to extensions/Math/modules/mediawiki-extensions directory

Change-Id:  I97d68c0555bc9fbdd6bf42912aa249d57b3d9359
Merge "Separating MediaWiki specific files from MathJax module"