Add default_client_name in Nova::FloatingIPAssoc

default_client_name has been missed, so stack fails
to delete, if server, from which floating ip association
depends, not exist.

Change-Id: I01bb91f8afaeb483e1a4bb55653dc3189a62bf12
Closes-bug: #1396982
Merge "Add default_client_name in Nova::FloatingIPAssoc"