No template caching for dev. Fix modal dismissal bugs.

* Add logic to disable angular modal template caching in development
  (when host="localhost").

* Disable modal dismissal on esc key and clicking backdrop.

* Change button elements in modals to "a" to disable activation on
  pressing "return" key.

* Either of the two aforementioned modal dismissal methods will create
  duplicate modals when the modal gets reappears.

* Add help info text to "start time" field of task modal.