Avoid UnicodeEncodeError exception on exception
Avoid UnicodeEncodeError exception on exception

When an exception message contained a non-ascii
character, the str() conversion raised an UnicodeEncodeError.

Avoid this by simply passing the message itself.
Python handles the encoding to locale already.

Change-Id: I3c4440fc238d8c8136a9bd93a0040668f82bda6e

varunarya10/python-cinderclient,ntt-sic/python-cinderclient,JioCloud/python-cinderclient,scottdangelo/cinderclient-api-microversions,citrix-openstack-build/python-cinderclient,metacloud/python-cinderclient,citrix-openstack-build/python-cinderclient,swamireddy/python-cinderclient,JioCloud/python-cinderclient,eayunstack/python-cinderclient,scottdangelo/cinderclient-api-microversions,swamireddy/python-cinderclient,eayunstack/python-cinderclient,metacloud/python-cinderclient,ntt-sic/python-cinderclient,varunarya10/python-cinderclient