Need refactoring NetDHCPAgent as net's property

[Mitsuru Kanabuchi]

Currently, the Neutron's DHCPAgent implemented as the NetDHCPAgent resource in Heat.

However, we discussed appropriate way of how to implement L3Agent in following review:
  https://review.openstack.org/#/c/69303/

The conclusion is to implement Neutron's L3Agent as router's property.
I think, we should refactor NetDHCPAgent in the same way as RouterL3Agent.

[1] Remove OS::Neutron::NetDHCPAgent resource from net.py
[2] Add "agent_ids" as property to OS::Neutron::Net. It's non-required list value because Neutron allowed multiple DHCPAgent to a network.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/81726

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/81726
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=988b71bd5a93050b4dc8b5f7fba6dbfa3e14c254
Submitter: Jenkins
Branch: master

commit 988b71bd5a93050b4dc8b5f7fba6dbfa3e14c254
Author: Mitsuru Kanabuchi <email address hidden>
Date: Mon Mar 24 12:05:33 2014 +0900

    Reimplement DHCPAgent as net's property

    We implemented Neutron's DHCPAgent resource as Heat's NetDHCPAgent resource at
    once.

      https://review.openstack.org/#/c/59626/

    However, we discussed appropriate way of how to implement L3Agent in the
    following review:

      https://review.openstack.org/#/c/69303/

    The conclusion is to implement Neutron's L3Agent as router's property.
    We should refactor NetDHCPAgent in the same way as RouterL3Agent.

    Change-Id: I7a0118ed4445b31186e24c545d4529867ce78c6c
    Closes-bug: #1294965