Google analytics

1. This is second pull request on this branch, I rebased the branch on top of master after Ross merged recently, so I had to kill the original pull request.  Same commits, different hashes.

2. COmmit covers:
   docs
   fixes to test_wsgi.py
   adding in a field to model called googleTrackingID, plus testing it for validity 

We do *not* currently do anything with the number stored.  It is expected iot will be templated into HTML page in webview