LBaaS: fix handling pending create/update members and health monitors

When agent requests loadbalancer logical config from server,
server returns only active pool members and health_monitors.
Need to make server return also members and monitors which are in pending states.

Also a small refactoring moving ACTIVE_PENDING set to common place

Change-Id: I8e10004f199f982b055da18ea7a0e5e4d11fa7fb
Closes-Bug: #1259965
NVP: Add LOG.exception to see why router was not created

Add missing LOG.exception so that it exposes what error occurred.

Change-Id: I9194795678a6be59eb1d2555dfa99ca7a035c418
Closes-bug: #1269152
Expunge session contents between plugin requests

In the NVP plugin, metadata processing performs several plugin operations
with the same context (and db session). The first operation might leave
persisted objects in the session instance which then conflict with objects
created in the second operation.

Closes-Bug: #1266482

Change-Id: Ic9e2b952013610647aa222f1a8b6e33504b54b37
Use an independent iptables lock per namespace

Since iptables is independent from namespace to namespace, it makes
sense to use an independent lock per namespace.  This improvement is
aimed at improving the parallel performance in the L3 agent.

Partially implements blueprint: neutron-tempest-parallel

Change-Id: I15e9c9da9a7c15981757a09bc744501722d62db2
Base ML2 bulk support on the loaded drivers

Changes the ML2 plugin bulk support flag to
be based on the bulk support of the underlying
drivers.

Closes-Bug: #1272490
Change-Id: I28281c9ecc1696b929c7e0125d02a37946948744
Configure floating IPs addresses after NAT rules

Change the behaviour of the L3 agent in order to set the IP addresses
for the floating IPs on the external gateway interface after the
relevant NAT rules have been applied.
This will avoid a transitory period in which the floating IP exists
and is reachable but it not yet wired to the actual target.

Partial-Bug: #1265505

Change-Id: Ib382fde021868bab2185f2fa5bdee86559148ba7
Fix error message typo

 * Fix error message typo in "_network_admin_state"
   function where "Network Admin State Validation Falied"
   should be changed to "Network Admin State Validation Failed"

Change-Id: I767e93c300250b4422e3980f799862ceb976c951
Closes-Bug: #1276409
Signed-off-by: Fawad Khaliq <fawad@plumgrid.com>
Merge "Base ML2 bulk support on the loaded drivers"
Merge "NVP: Add LOG.exception to see why router was not created"
Merge "Use an independent iptables lock per namespace"
Merge "Configure floating IPs addresses after NAT rules"
Merge "Fix error message typo"
Merge "Expunge session contents between plugin requests"
Merge "LBaaS: fix handling pending create/update members and health monitors"