Add EventDrop#created_at and drop (skip_)created_at from EventFormattingAgent.
Allow HipchatAgent to use a shared credential
Add Bountysource link/badge to README
Break Diagram into it's own controller, nest resources

Conflicts:
	app/views/scenarios/show.html.erb
Merge pull request #417 from knu/add_created_at_to_event_drop

Add EventDrop#created_at and drop (skip_)created_at from EventFormattingAgent.
remove created_at from default options
Merge pull request #419 from drcapulet/hipchat-shared

Allow HipchatAgent to use a shared credential
Merge pull request #422 from drcapulet/route-changes

Break Diagram into it's own controller, nest resources