[Drive] Added Drive API and demo

* Removed GAPI button from main.html
* Added GAPI button to top navigation
* Added Bootstrap classes for decent layout
* Added Drive Controller & partial
* Updated $RouteProvider to use Drive partial and controller

Description:
  Adding basic bootstrap and demo of the Google Drive API. A preview
  section for the list and a preview of the files/folders in the main
  Drive folder are requested and only the 'listFiles' method
  has been added in this demo.