Add notice about Analytics data

[paolorotolo]

From Google's documentation:

You will give your end users proper notice about the implementations and features of Google Analytics you use (e.g. notice about what data you will collect via Google Analytics, and whether this data can be connected to other data you have about the end user). You will either get consent from your end users, or provide them with the opportunity to opt-out from the implementations and features you use.

[paolorotolo]

Fix merged in develop, thanks @chwalters!