Updating CLS specific layout and pages to use Help css and layout.

Changed the CLS specific page layout to include a menu link to the main Help site. Converted to use main site CSS and added CLS specific styles into CSS. Changed fixed width font to use web font. Tidied up java script, and some general layout quirks.

To test:
For /cls-getting started.html and /cls-public-demo.html
- check link in left hand menu
- check email links in text
- check code-style (fixed width font) sections are displaying correctly
- check "200" is displaying in red in second URL example in cls-public-demo.html 
wrong link