Log methods using rpc communcation

In Icehouse was used rpc library from oslo-incubator. Because the code
wasn't mature enough it was running in DEBUG mode. After migrating to
oslo.messaging we don't need to have debug level in oslo.messaging but
it's good to have communication logged.

Closes-Bug: #1340696
Change-Id: I4f68545053912f96affc1bbcd64fcd7efe8d18c0
OFAgent: Share codes of l2-population in OVS agent

This is step 1 implementation of OFAgent l2-population.
OFAgent partially uses codes in OVS agent on implementation of l2-population.
We share these codes adding mixin class for OVS to l2-population rpc.
We use a ryu library instead of executing a ovs-vsctl command
and on OFAgent l2-population is no longer optional.
Also a function of local arp responder will be implemented on step 2.

related commit: b6133c35dd587f6b01e8ec12757347b2767713a6

Partially implements: blueprint ofagent-l2pop

Change-Id: I99a2adfd380a9fefe34c53e0dabc21d8cf5936cc
Move loadbalancer vip port creation outside of transaction

Currently _create_port_for_vip calls ml2 create_port() method
which includes rpc notification.
That leads to lock wait timeouts in certain cases.

The patch fixes that while making VIP creation process non-atomic.
But that is fine as long until create_vip() returns vip id, it's
not usable from API.

Change-Id: Ie30973de80118a6b022e8c3bb07ca48122ebcd29
Partial-Bug: #1334226
Merge "OFAgent: Share codes of l2-population in OVS agent"
Correct misspelled variable name

In neutron/services/loadbalancer/drivers/embrane/driver.py,
"persistence" is wrote with an "a", not with an "e".
This patch fix this.

Change-Id: I8da0d6d28c188c73ed844a8a0c7a523dae713344
Merge "Move loadbalancer vip port creation outside of transaction"
Merge "Correct misspelled variable name"
Merge "Log methods using rpc communcation"