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This global is not used anymore as it's been replaced by a similar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
Update mailmap

Update mailmap and keep this file
in alphabetical order.

Change-Id: I657b83202de3fdf6f4624567dfa8a53ca3ea5b39
Imported Translations from Transifex

Change-Id: Ie1d6b2c1f158609b9bb58aedec542060ce2cd2e7
Merge "Remove global DB_ENGINE from Neutron"
Merge "Update mailmap"
Merge "Imported Translations from Transifex"
Add multiple provider network extension

The following commit adds the ability to associate multiple
different provider networks on a single network.

Implements blueprint map-networks-to-multiple-provider-networks

Change-Id: I3c70fb2426899f728a401566debab7f66e7246bc
Enable GRE and VXLAN with the same ID

Current packet processing in br-tun is based on tun-id,
as a consequence, two networks using different tunnel
types but sharing the same tun-id would not be properly isolated.

To ensure proper isolation within a single bridge, NORMAL action
can't be used any more as it floods unknown unicasts on all
bridges ports. It is replaced by a learn action that dynamically
sets-up flows when packets are recieved from tunnel ports. As mac
address are learnt in explicit flows (in table 20), we can use a
default action in that table to flood unknown unicasts to the
right set of ports, like broadcasts and multicasts packets.

See https://wiki.openstack.org/wiki/Ovs-flow-logic for a more
detailled explanation of the flow logic

Another alternative could have been to use distinct bridges for
each tunnel type (whithout modifying the current flow logic),
but previous alternative may be preferable as it paves the way
for new tunneling optimisations (like RPC based mac learning and
partial-mesh flooding proposed in bp/l2-population)

Change-Id: I1dfe74f96680c2c6fe4d8d4aac4821c6b020c005
Closes-Bug: #1196963