Quick Fix - Task Editing Cancel

Temp fix for #1599

Hides the edit button on task editing.
Shows new cancel button on task editing.
Hides task notes on task editing.

Notes:
Still needs a save button up top, ```save(task)``` didn't seem to be working with ng-click (also tried a couple other things.) Will revisit.
'ng-if's could also work instead of 'ng-hide's.
Decided that we don't really need to have the task notes popover display while editing tasks since that stuff is already in the task editing pane.