enable multiple role assignment.
case neutron-l3 is assigned before neutron-server.
Merge pull request #58 from MaximilianMeister/neutron-multiple-roles-bug

multiple assignment bug
Removed the single assignment block from constraints
Merge pull request #59 from tboerger/feature/roxy/fix-constraints

Removed the single assignment block from constraints
Fix to work when keystone is behind haproxy
Use new helpers to get hostnames for endpoints
HAProxy support for neutron-server
Use correct nova host when nova is behind haproxy