webadmin: Generalize messaging server broker type

Since we intend to support additional messaging broker
types (i.e. RabbitMQ), there is a need to update all
references to the messaging configuration.

Change-Id: I0a18937e5174b5cf95e99b4959f622f368a333c0
Signed-off-by: Moti Asayag <masayag@redhat.com>
webadmin: Add broker type to neutron agent configuration

The broker type was added to neutron agent configuration
so additional broker types could be supported.

Change-Id: I04966edaebd4c9d260bbb42cae16ef3a42467ce3
Signed-off-by: Moti Asayag <masayag@redhat.com>