Committing work by Arnfried (EXCELLENT!) 
I made a few minor modifications, mostly style.

BIG kuddos to arni for his amazing work on the plugin and 
integrating all feedback from code reviews and Piwik Mobile integration brainstorms!!

git-svn-id: http://dev.piwik.org/svn/trunk@5292 59fd770c-687e-43c8-a1e3-f5a4ff64c105