Set storage protocol to ceph for ceph based setups

There might not be any iscsi backend configured
then.
Add optional crowbar-applied boolean attribute to schema

Set it to false by default in the json and update proposal schema
version to 3.
Merge pull request #91 from dirkmueller/ceph

Set storage protocol to ceph for ceph based setups
Merge pull request #92 from dirkmueller/attrib

Add optional crowbar-applied boolean attribute to schema