Comments UI

- Added comments resource
- Added comment list controller to resolve author names.
- Updated detail controller to allow comment control.
- Major rework of the story UI to make room for a tasks and discussions.
- Refactor of story controllers to separate concernse into tasks, comments, story.
- Collapse of the story statechart.
- New LESS file for discussions.
- New directive: ngShiftEnter, to allow shift-enter comment submission.
- New directive: contenteditable, to allow in-context editing.

Change-Id: I8be85da39097683eb7660835c1cbc40524dd5b2c