Apply Oslo ModelBase to NeutronBase

Oslo.db has ModelBase which implements most of NeutronBase's code.
Therefore NeutronBase should inherit from ModelBase to keep things DRY.

Fixes bug #1171055

Change-Id: I1a08636a6aa225da8b5d43a0bbcb9b59c057df42
Register agent schedulers options in one place

Currently agent schedulers options are defined in neutron.scheduler and
every plugin that supports scheduling should register them individually.
It is reasonable to define and register options in one place - agentschedulers_db.

Fixes NeutronManagerTestCase when running separately by importing missing config option

Fixes bug 1198904

Change-Id: Ia9c1ad3fb4b71796401ef5507f741f3cc024a4da
port-update fails when using SELECT FOR UPDATE lock

In Postgresql, it will throw the bellow exception when
using SELECT FOR UPDATE lock combined with outer join.
"SELECT FOR UPDATE/SHARE cannot be applied to the
 nullable side of an outer join"

The reason can refer http://www.postgresql.org/ \
message-id/21634.1160151923@sss.pgh.pa.us

for this issue, I don't think outer join is necessary，
so I change it to use inner join.

Fixes bug #1191653

Change-Id: Ifc9ecad91324ce28399431ea77fe0865b6d8e523
Add status description field for lbaas objects

Fixes bug 1166925

Change-Id: I44d936afd8cd531a786c09c38bbc4702737ce99c
rename quantum into neutron

Bug #1200474

Change-Id: Ib83e58008fc53b57c4063057ce4c5707b55f0ff2
Merge "rename quantum into neutron"
Merge "Apply Oslo ModelBase to NeutronBase"
Merge "port-update fails when using SELECT FOR UPDATE lock"
Merge "Add status description field for lbaas objects"
Merge "Register agent schedulers options in one place"