Add support for NSX/NVP DHCP services

This is a feature patch (1 of 3) that adds support for DHCP
services provided by the NSX (aka NVP) platform. Green-field
deployments can use the AGENTLESS mode, which will make the
core plugin interact solely with the NSX platform to provide
DHCP services. Support for metadata proxy services, migration
for brown field deployments will be added in future patches.

Partial-implements blueprint nsx-integrated-services

Change-Id: Idfc4b2d871e70cd557d8e0e6b23e5563f9ed3420
Pass in certain ICMPv6 types by default

This allows instances to do SLAAC configuration, without requiring
explicit security group rules to do so.

Closes-Bug: #1242933

Change-Id: I517c66a470296141c0024a64e39b6d40b0c0d581
Updates .gitignore

To ignore swap files from getting into repository
currently the implemented ignores are *.swp and *.swo
however vim adds more swap files if these files exists,
so improving this with *.sw?

Change-Id: Ie1b458d2b862e6cf2552ae5be6c6178b72e960ab
Closes-Bug: #1255876
Improve OVS agent logging for profiling

This patch adds some debug logging statements aimed at profiling
tasks in the agent's main rpc loop.
These logging capabilities will help gain some better insights into
the performance bottlenecks of the agent.

Part of blueprint neutron-tempest-parallel

Change-Id: Ied04b906dbbb9993283981bdee6c96e43a7d19a3
Merge "Add support for NSX/NVP DHCP services"
Merge "Improve OVS agent logging for profiling"
Imported Translations from Transifex

Change-Id: Ib10116cf71536ff8af7e09af257169057371448e
Merge "Pass in certain ICMPv6 types by default"
Merge "Updates .gitignore"
Merge "Imported Translations from Transifex"
Merge branch 'master' of https://github.com/openstack/neutron into odl_ml2