final registrations stats

Conflicts:

	app/views/admin/stats/index.html.haml
Create charts for registrations

Conflicts:

	app/controllers/admin/stats_controller.rb
	app/views/admin/stats/index.html.haml
add d3 lib
Merge pull request #55 from differentreality/stats_charts

Stats charts for registrations (Admin)
Release osem under MIT. Fixes #57
Fix managing user roles
Updated the gems, add missing migration for the stats controller, fix most obvious issues with stats
Show the supporter_level title, not the class
Update README.md