Use get_password method to obtain qpid password

Currently, qpid's password is stored in an attribute in the common
cookbook.  This change causes the password to be looked up via
get_password method, which is how we obtain the rabbitmq password.

Change-Id: Iff7c72663472af677da6d542a9826d599e8ed810
Implements: blueprint use-data-bag-for-qpid-password
Handle Ceph-related steps for using the RBD store

With this change, the api recipe will take care of the ceph-related
things when the default_store attribute is set to rbd:

- install dependency packages as specified in
  openstack[image][platform][ceph_packages]
- create a cephx client keyring file with openstack-common's template
  and the key found in the data bag specified by the newly introduced
  attribute openstack[image][api][rbd][key_name]

Change-Id: I92881e5a27fb5ec56d4f1fb72933749a3e8d8688
Add filesystem_store_datadir initialization

Add initialization of filesystem_store_datadir directory with proper
owner and permission settings.

Partially implements: blueprint gpfs-storage-support
Change-Id: I858b7877a4174491db546dcf7aff8b2817b8c08d