UI navigation is improved

* Introduce AJAX-based drop-downs
* Introduced drop-downs for modules, companies and engineers
* Introduced AJAX methods for retrieval of modules, companies,
  engineers, contribution and activity logs
* Removed unused scripts and templates

Implements blueprint improve-navigation

Change-Id: Icef6433dbc2763241c99be83d5549c1e7eac4a76
Merge "UI navigation is improved"