Jetpack: Holiday Snow: Add an adminbar item of a snowflake if the user can control the snow being active, they are in wp-admin, and it is currently 
active.  Also add a fun spinning animation on hover to it.  Clicking takes them to the setting that explains what's going on with the snow on their 
site.


git-svn-id: https://plugins.svn.wordpress.org/jetpack/trunk@807935 b8457f37-d9ea-0310-8a92-e5e31aec5664