#477830: Followup, no need to clear JS cache as ga.js is not aggregated with core.

* Fixed broken ga.js URL if i18n language path prefix is used.
* Added dummy query-string to ga.js to gain control over browser-caching.

#811156 by hass: Found some people reporting that _gaq.push(["_gat._anonymizeIp"]) works in async code.

- Invoke all modules with hook_load_profile to extend the $user object with trackable data.
- Refactoring $fields array building.
- Only select used fields from profile_field table.