Show and select google calendars in account modal.

* Pull calendar names from Google API and present them to be selected.
  Calendar selections are only persisted on the client side.
  TODO: persist calendar ids to server.

* Initialize "$auth.user.gcals" variable in run block and on login/
  signup.

* Use an angular event to signal to a nested "googleCalSelectCtrl"
  controller when "user" model has been initialized in
  "accountModalCtrl".

* Update account modal form styles.