Added option to anonymize IP addresses.

This is done using the anonymizeIP module of Google Analytics. Setting
such option is mandatory in certain countries (e.g. Germany) if you want
to use Google Analytics due to national data privacy laws
Update version number
Added opt-out functionality by means of a cookie

This is also necessary in some countries, e.g. Germany. I have added a
section in the FAQ on how this can be called by a user.

See (in german):
https://www.datenschutzbeauftragter-info.de/fachbeitraege/google-analytics-datenschutzkonform-einsetzen/
http://rechtsanwalt-schwenke.de/google-analytics-rechtssicher-nutzen-anleitung-fuer-webmaster/

See google analytics docs for this is done:
https://developers.google.com/analytics/devguides/collection/gajs/?hl=en#disable