Send proper exception info as expected by the neutron client

The python neutron client for the V2 API expects the neutron API
to send information back such as the type and detail of the exception
in the body of the message

Change-Id: I9486d757258c4be72799c41102babe1f7923121c
Closes-bug: #1226400
Allowed Address Pairs support in NEC plugin

Closes-Bug: #1230184
Change-Id: I84d4dda9f88f7bbb524e173b0274db013f69b7e3
Redefine behavior for NvpAdvancedPlugin during network creation

When using the NvpAdvancedPlugin, *all* logical switches should
be created through VCNS. VCNS will then proxy the requests to
NVP. This patch implements such a behavior. This is achieved by
replacing the use of nvplib.create_lswitch with the one of the
vcns driver, as the remaining logic can be left as it is.

Fixes bug #1225011

Change-Id: I6c276f747d02ac0d4934c38bf2858cf9b73c5e24
Raise an exception if no router_id provided

IF both service neutron-l3-agent and neutron-server are up,
but no router id configured in /etc/neutron/l3_agent.ini, an
exception will be raised on DB as "DBError: IntegrityError",
because the variable router_ids has a default '' value that
doesn't match the DB grammar.

    * Check router id is specified in _init_() of l3 when
      not using namespace.
    * Move part of checking config params actions to new function
      _check_config_params()
    * Add corresponding unit tests.

Closes-Bug: #1226366

Change-Id: I905f8a4061c5b250782e025681dfefcc41c8c03c
Merge "Allowed Address Pairs support in NEC plugin"
Merge "Send proper exception info as expected by the neutron client"
Merge "Redefine behavior for NvpAdvancedPlugin during network creation"
Merge "Raise an exception if no router_id provided"