Config properties are now in constants, and 1st implem of persistent
storage.
Enhanced support for persistent volumes.
Removed useless code.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	roboconf-iaas-openstack/src/main/java/net/roboconf/iaas/openstack/IaasOpenstack.java
Merge pull request #82 from gibello/master

Add volumes to OpenStack Iaas + some cleanup