Handle error with non existing template file

This patch allows to propagate IOError instead of returning
TemplateResource which does not contain property_schema.
Change-Id: Ib1e09de8c10672312eea09f62a28f0885d98b089
Closes-Bug: #1394552
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"
Merge "Handle error with non existing template file"