Remove RPC to plugin when dhcp sets default route

_set_default_route() was using an RPC to the plugin to get the DHCP
port for the network on the current host, and then used it to form
the tap device name. This happened on every allocation reload too.
This fix removes the RPC and gets the tap device name using local
methods instead. It also removes an unnecessary call to set the
default route in the restart method.

Closes-Bug: 1290068
Related-Bug: 1294254
Change-Id: I639bcf93725c4969d1011d2d20491d461ccfdbed
Enable flake8 E711 and E712 checking

E711 comparison to False should be 'if cond is False:' or 'if not cond:'
     comparison to None should be 'if cond is None:' or 'if not cond:'
E712 comparison to True should be 'if cond is True:' or 'if cond:'

Most violations were in DB queries. Replace as follows:
  False -> sqlalchemy.sql.false()
  None  -> sqlalchemy.sql.null()
  True  -> sqlalchemy.sql.true()

Change-Id: Iff54747b70f504d5466cfdc6e2ec4d7a0f9ddb7c
Closes-bug: #1305377
OFAgent: Process port_update notifications in the main agent loop

Port the following patch to OFAgent.
commit: 5e6e592132aa9a98936ce3bfdb66efc7832caafb
https://review.openstack.org/#/c/61964/

Partial-Bug: 1293265

Change-Id: I53813d12c66dc746cd373fd91ff9bd9bdbf222db
OFAgent: Improve handling of security group updates

Port the following patch to OFAgent.
commit: 3046c4ae22b10f9e4fa83a47bfe089554d4a4681
https://review.openstack.org/#/c/63100/

Partial-Bug: 1293265

Change-Id: Iecdfee894ff2fd5f05f63f040dd70821af124737
Make help texts more descriptive in Metaplugin

This patch makes help texts of configuration parameters of
metaplugin.ini more descriptive. Comments in metaplugin.ini
are also improved.

Change-Id: I1fac888ecc223a7199cc9c9aeb603b7493f22171
Closes-Bug: #1283930
Updated from global requirements

Change-Id: I11182ae01c05ed104b064c2b68bcbf5a53e0da99
Ml2: Set correct nullable for admin_state_up

In migrations 492a106273f8_brocade_ml2_mech_dri was set incorrect
nullable parameter:

Set admin_state_up NOT NULL in ml2_brocadeports.

Partial-Bug: #1296282

Change-Id: I051e37990ae3371978eeb1ff71e70ae2a44097bc
Cisco: Set correct nullable for switch_ip, instance_id, vlan_id

Corrected the following model according to database
content:
 - NOT NULL for NexusPortBinding switch_ip and instance_id

In migrations folsom_initial was set incorrect nullable parameter:
- Set vlan_id NOT NULL in cisco_nexusport_bindings.

Partial-Bug: #1296282

Change-Id: Ie5315fcbf227025c30ab4a4b97ec2a140ee3923c
Fix H302 violations in db package and services

Change-Id: If5e07fa4529430ba90d9c7dd81d28ceeee00ebe0
Partial-Bug: #1291032
ip-lib : use "ip neigh replace" instead of "ip neigh add"

Closes bug #1311002

Change-Id: Ie50bc0bff32b7f97ac317ccc2521bbea52d59ca3
Merge "Ml2: Set correct nullable for admin_state_up"
Merge "Remove RPC to plugin when dhcp sets default route"
Merge "ip-lib : use "ip neigh replace" instead of "ip neigh add""
Merge "Cisco: Set correct nullable for switch_ip, instance_id, vlan_id"
Merge "Updated from global requirements"
Merge "Enable flake8 E711 and E712 checking"
Merge "Fix H302 violations in db package and services"
Merge "Make help texts more descriptive in Metaplugin"
Merge "OFAgent: Process port_update notifications in the main agent loop"
Merge "OFAgent: Improve handling of security group updates"