Implements fix to run lbaas service on fedora with devstack

changes 'user_group = nobody' in 'haproxy' section of lbaas_agent.ini

Change-Id: I801fec5a11d8abd97cb6f5cdff35fabb9eaf9000
Closes-Bug: 1283064
Fix libvirt polkit settings

After the https://review.openstack.org/#/c/75314 merged
the /etc/polkit-1/rules.d/50-libvirt-stack.rules files contains
subject.user == '"stack"' instead of
subject.user == 'stack'.

Change-Id: I09f252b2d0e53f012facb9f7eaa21c1e1bdf492b
Merge "Implements fix to run lbaas service on fedora with devstack"
Merge "Fix libvirt polkit settings"