Fixed minor typos with trove-client help info
Fixed minor typos with trove-client help info

Fixed typos and cleaned up unnecessary imports.

Fixes bug 1238325

Change-Id: I7b2379cecb89e9f58cde9b2b68bddee41aefcfa3

metacloud/python-troveclient,metacloud/python-troveclient,cp16net/python-troveclient,openstack/python-troveclient,Tesora/tesora-python-troveclient,Tesora/tesora-python-troveclient,cp16net/python-troveclient,openstack/python-troveclient