Add Google Analytics RequireJS module

- Add a new ga.js RequireJS module for loading Google Analytics
  asynchronously. Even though it already loads asynchronously, this
  gives us a hook to more easily automatically run logic on every
  page load
- Repalce direct GA usage in HTML pages via <script> tag with usage of
  the RequireJS module; add a stub-ga.js RequireJS main module for this
  for pages that do not otherwise use JS (e.g. /faq)
Add 'noga' cookie

- If the ga.js module sees a 'noga' cookie set, return undefined from
  the loader. The idea here is to avoid counting CrimeDB developers in
  the Google Analytics stats
- Set the noga cookie in httpd.conf for www.crimedb.org