installation: upgrade to local/CDN MathJax 1.1
- Updates install script to work with MathJax 1.1 (from GitHub). Adds new CFG_MATHJAX_HOSTING variable to choose between locally hosted MathJax and CDN served MathJax libraries. (closes #550)
- Note: local MathJax 1.1 seems to crash Google Chrome 10.0.648.204 on Linux. YMMV.