Remove global DB_ENGINE from Neutron

Related-Bug 1207402

This global is not used anymore as it's been replaced by a similar
global variable in neutron/openstack/common/db/sqlalchemy/session.py

Change-Id: Id4614069af490020d18f14011853787930076e0a
Fix ML2 VXLAN TypeDriver DB migration

The migration for the ML2 VXLAN TypeDriver was incorrectly setting
primary key attributes on separate lines for 'ip_address' and
'udp_port'. Also, a primary key cannot have autoincrement set, so
add this to 'udp_port' as well.

Fixes bug 1213134

Change-Id: I0b2e2685bf524dd9c0333ac4511287ad6a5eb87e
Ensure nvp resources are tagged with an up-to-date version of Neutron

This is made possible by using version.version_info

Fixes bug #1213242

Change-Id: Iad75f7c6f6c045a2f473388529174cf02f413899
Fix wrong example in HACKING.rst

Example of Human Alphabetical Order Examples section in HACKING.rst
is wrong, this patch fixes it to the right order.

Closes-Bug: #1213568

Change-Id: Ib7f8baf20c437c3fa776201998c36f33bdde2f78
Set BigSwitch plugin to use existing host database model

The BigSwitch plugin had a data model duplicating one
that was recently added into the base portbindings db
file. This patch removes the BigSwitch model and
updates the BigSwitch plugin to reference the plugin-
agnostic model.

Fixes: bug #1211641
Change-Id: I1fdbf8690e71fb2d6e9d6a6dbd0571fa2c32a7e0
Imported Translations from Transifex

Change-Id: Ib9d5a27121f3b0bfa269ccbdd15cec0e42ffe3bc
Enable SNAT by default in L3 agents

If ext-gw-mode extension isn't supported by plugin, it won't
return enable_snat param in router info. Agent will currently
default to enable_snat = false, which changes from expected
default behaviour prior to ext-gw-mode introduction.

This patch changes L3 agent to enable SNAT by default if plugin
doesn't support ext-gw-mode extension.

Change-Id: I35e8f8c20392bff9ac2f875f2c9a1038ab06ad7b
Closes-Bug: #1212868
Update mailmap

Update mailmap and keep this file
in alphabetical order.

Change-Id: I657b83202de3fdf6f4624567dfa8a53ca3ea5b39
Merge "Fix wrong example in HACKING.rst"
Merge "Imported Translations from Transifex"
Merge "Set BigSwitch plugin to use existing host database model"
Merge "Enable SNAT by default in L3 agents"
Merge "Ensure nvp resources are tagged with an up-to-date version of Neutron"
Merge "Fix ML2 VXLAN TypeDriver DB migration"
Merge "Remove global DB_ENGINE from Neutron"
Merge "Update mailmap"