Port to database barclamp

A good part of this was made by Ralf Haferkamp <rhafer@suse.de>
Create a proposal when only when the dependendencies are satisfied (bnc#773803)
The database setup needs only be executed on the control node (bnc#780406)

Running the nova::database recipe on every compute is not required and causes
problems with the current postgresql release. The compute nodes only need the
database client packages installed. The database setup is already done by the
controller cookbook which gets executed before nova::compute.

https://bugzilla.novell.com/show_bug.cgi?id=780406
Merge pull request #152 from vuntz/database-barclamp

Port to database barclamp