Use six.moves cStringIO instead of cStringIO
Use six.moves cStringIO instead of cStringIO

to keep Python 3.x compatibility, use six.moves.cStringIO to
replace StringIO

Change-Id: I900d9b90665c13770ae770d53ff67c2ae3df8b9d
Closes-Bug: #1280964

noironetworks/heat,pshchelo/heat,steveb/heat,jasondunsmore/heat,dims/heat,pratikmallya/heat,rh-s/heat,NeCTAR-RC/heat,takeshineshiro/heat,rh-s/heat,gonzolino/heat,dragorosson/heat,redhat-openstack/heat,rdo-management/heat,srznew/heat,maestro-hybrid-cloud/heat,NeCTAR-RC/heat,srznew/heat,dims/heat,pshchelo/heat,cwolferh/heat-scratch,cwolferh/heat-scratch,dragorosson/heat,cryptickp/heat,cryptickp/heat,openstack/heat,miguelgrinberg/heat,takeshineshiro/heat,steveb/heat,miguelgrinberg/heat,noironetworks/heat,rdo-management/heat,maestro-hybrid-cloud/heat,jasondunsmore/heat,redhat-openstack/heat,pratikmallya/heat,openstack/heat,gonzolino/heat