Import nova exceptions as our own, so they can be used by importing from our client directly.
Import nova exceptions as our own, so they can be used by importing from our client directly.

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