Database barclamp conversion
Initial SUSE support for quantum barclamp and fix database detection stuff.

This commit introduces attributes for system specific settings like:
- quantum user name
- quantum services package name
- quantum services system name

All those setting ale placed in default[:quantum][:platform] tree.

There's also a small fir for detecting sql backend.
Remove duplicated service resource for quantum_agent in common_install
Merge pull request #37 from tpaszkowski/pull-req-quantum-suse-support

Initial SUSE support for quantum barclamp and fix database detection stuff.