update integration list in README
update integration list in README

current integration list in README.rst is outdated.

Change-Id: Iaf396f936ae512cdcfbcdd8d7a023c4914a02361

dragorosson/heat,cryptickp/heat,pratikmallya/heat,cryptickp/heat,cwolferh/heat-scratch,takeshineshiro/heat,noironetworks/heat,maestro-hybrid-cloud/heat,takeshineshiro/heat,cwolferh/heat-scratch,dims/heat,maestro-hybrid-cloud/heat,gonzolino/heat,pratikmallya/heat,steveb/heat,jasondunsmore/heat,dims/heat,openstack/heat,openstack/heat,gonzolino/heat,jasondunsmore/heat,dragorosson/heat,steveb/heat,noironetworks/heat