acceptance: bump trusty packaging to trusty-proposed/liberty
acceptance: bump trusty packaging to trusty-proposed/liberty

Since our recent discussion about Ubuntu packaging, we decided to bump
Ubuntu packaging to trusty-proposed/liberty so we can install Liberty in
a better shape than current situation (Staging repo).

This patch installs UCA liberty repository.

Depends-On: I57e2ddc5d0e228142f8045623ffbde362c0e7f7b
Change-Id: I7ebbda36560ab5269d60747782dba2771147103c
fuel-infra/puppet-neutron,IPnett/puppet-neutron,CiscoSystems/puppet-neutron,rdo-puppet-modules/puppet-neutron,fuel-infra/puppet-neutron,IPnett/puppet-neutron,rdo-puppet-modules/puppet-neutron,CiscoSystems/puppet-neutron,plumgrid/puppet-neutron,fuel-infra/puppet-neutron,openstack/puppet-neutron,plumgrid/puppet-neutron,IPnett/puppet-neutron,CiscoSystems/puppet-neutron,openstack/puppet-neutron