Port to database barclamp

A lot of this was done by Ralf Haferkamp <rhafer@suse.de>
Disallow SQLite based setup

Conflicts:
	crowbar_framework/app/models/nova_dashboard_service.rb
	crowbar_framework/app/views/barclamp/nova_dashboard/_edit_attributes.html.haml
Create a proposal only when the dependencies are satified (bnc#773803)

Conflicts:
	crowbar_framework/app/models/nova_dashboard_service.rb
Merge pull request #70 from vuntz/database-barclamp

Port to database barclamp