Remove Google analytics from base code

As per Mozilla's request:

3) Google Analytics as Remote Script / CSP
Using a remote script for Google Analytics is not allowed. We don't allow add-ons to use remote scripts because they can create serious security vulnerabilities. Please see https://blog.mozilla.org/addons/2016/05/31/using-google-analytics-in-extensions/ for an approved method and remove Google Analytics from the CSP declaration.

scripts/popup.js line 31, 32, 33

5) We don't allow add-ons to use remote scripts because they can create serious security vulnerabilities. We also need to review all add-on code, and this makes it much more difficult. Please insert those scripts locally from your add-on code. If you are using a custom Content Security Policy that allows remote script execution, please adapt it accordingly.

scripts/popup.js line 31, 32, 33