Fix docstrings in keystoneclient
Fix docstrings in keystoneclient

Trusts and service catalog had a few malformed docstrings
that caused warnings when building docs.

Change-Id: Iea8612c3aaebea54c00b02c73c77f0c9e79f86bc
Partial-Bug: #1315523

sileht/keystoneauth,citrix-openstack-build/keystoneauth,jamielennox/keystoneauth