Increase IP binding flexibility changes

Changes have been made to the common cookbook so that if a
bind_interface is specified for an endpoint, then the IP is looked up
for that endpoint using address_for, and if no bind_interface is
specified then the value of the host attribute of the endpoint is used
instead.

This change set removes code around the network API endpoint that
implements this exact behavior, which is no longer needed since it is
now provided by the common cookbook.  This change set also replaces
direct calls to address_for by the OVS and LinuxBridge code with
endpoints.  This allows the user to either specify an interface or an
IP to bind to using the standard endpoint library for these two
plugins.

This change is dependent on change: https://review.openstack.org/83859

blueprint increase-ip-binding-flexibility

Change-Id: Ie0aa07ab511c4ccbe9686da4dfb05934f9708b9a
Subscribe Neutron agent services to neutron.conf

Before this change, a change to neutron.conf would not cause any agent
to restart. I doubt this was intended, since for example changing
rabbitmq stuff in neutron.conf really needs the agent to restart to have
any effect.

Furthermore, the balancer recipe subscription/notification logic has
been changed to fit in line with the other agents, i.e. having the ini
template notify the service and the service subscribe to neutron.conf.

Change-Id: I2d5b20a13945fb8a360b81091e68e0fcf5748e93
Closes-Bug: #1300076
Merge "Increase IP binding flexibility changes"