LBaaS: when returning VIP include session_persistence even if None

Closes-Bug: #1231915
Change-Id: I3dc5e17118995fb49dd381d08c9d92cb60b80abb
Move Loadbalancer Noop driver to the unit tests

Move Loadbalancer Noop driver to the corresponding folder in
unit tests to clearly indicate that it is an utility driver
that only suitable for unit testing.

Closes-Bug: #1250767
Change-Id: Ide2ebf212193f2cf5da9cf7a7f068fd918a55ada
Ensure get_pid_to_kill works with rootwrap script

To ensure that correct process is killed when using a rootwrap
script, we must recursively list the children of our top-level
process and kill the last one. This patch uses the psutil python
module which is already used in the heat-cfntools project.

Change-Id: I702bb9dd794c08fcaab637284ee303de1778cbb9
Add configurable ovsdb monitor respawn interval

If minimize_polling=True and the ovsdb-client process died, the
default respawn interval of 0 would mean that we'd start polling
again. This patch adds the option ovsdb_monitor_respawn_interval and
defaults it to 30 seconds.

Change-Id: I12c1e05ec4d6d2bd4d84024a91116e2ac3974868
Close-Bug: 1243867
Enable polling minimization

In some cases the OVS agent might end up wiring a port for a VM
several seconds after the VM has booted. As a result, there is a
risk that the VM won't receive an IP address from DHCP in time.

This patch changes the default value for agent.minimize_polling to
True. This change should reduce the time needed for configuring
an interface on br-int consistently.

Change-Id: I009f606fd34a132376f1d50f8ccda9d35d064bfa
Related-bug: 1224001
Merge "Move Loadbalancer Noop driver to the unit tests"
Merge "Add configurable ovsdb monitor respawn interval"
Merge "Enable polling minimization"
Merge "LBaaS: when returning VIP include session_persistence even if None"