Update analytics documentation
Wanted to point someone to google analytics for their site on the Commons, and realized we need to make some updates:
-- http://codex.commons.gc.cuny.edu/2012/12/22/statistics-for-your-site/ - this page starts with FireStats, which we've removed from the site (please do a search of the site documentation to see whether we mention it elsewhere
-- http://news.commons.gc.cuny.edu/2013/02/07/new-analytics/ -- this says that the way to set up analytics is to contact Brian, which obviously won't do now.
-- putting Dom as a watcher since he is working on some documentation for site developers