add _gat._anonymizeIp to google analytics config

This settings is to enable google analytics to anonymize IPs.

https://developers.google.com/analytics/devguides/collection/gajs/methods/gaJSApi_gat#_gat._anonymizelp
The documentation says: "While Analytics is loading, commands will be pushed/queued onto the array. When Analytics finishes loading, it replaces the array with the _gaq object and executes all the queued commands. 
`Subsequent calls to _gaq.push resolve to this function, which executes commands as they are pushed.` 
If this means the order of the array is the order of execution @peterflynn seems right and I'd agree with the order he proposed.