The OpenDaylight Neutron Service doesn't support IPV6

The OpenDaylight Neutron service doesn't support IPV6 subnets.

First, the ODL MechanismDriver is ignoring 400 errors. To get past that, apply this [1] diff to the driver. Once you do that, creating a subnet with IPV6 fails in ODL. The steps to reproduce are:

neutron net-create v6net
neutron subnet-create --name v6subnet --gateway 2003::1 --allocation-pool start=2003::2,end=2003::ffff:ffff:ffff:fffe --ip-version 6 v6net 2003::/64

Looking at a dump of the return from ODL, I see this:

0x0000: 4500 00ea 3d1b 4000 4006 0b8e c0a8 380a E...=.@.@.....8.
0x0010: c0a8 380a 1f90 be66 ec11 f2b3 9148 3190 ..8....f.....H1.
0x0020: 8018 0164 f241 0000 0101 080a 04ed cfaf ...d.A..........
0x0030: 04ed cfa9 4854 5450 2f31 2e31 2034 3030 ....HTTP/1.1.400
0x0040: 2042 6164 2052 6571 7565 7374 0d0a 5365 .Bad.Request..Se
0x0050: 7276 6572 3a20 4170 6163 6865 2d43 6f79 rver:.Apache-Coy
0x0060: 6f74 652f 312e 310d 0a43 6f6e 7465 6e74 ote/1.1..Content
0x0070: 2d54 7970 653a 2074 6578 742f 706c 6169 -Type:.text/plai
0x0080: 6e0d 0a54 7261 6e73 6665 722d 456e 636f n..Transfer-Enco
0x0090: 6469 6e67 3a20 6368 756e 6b65 640d 0a44 ding:.chunked..D
0x00a0: 6174 653a 2046 7269 2c20 3331 204f 6374 ate:.Fri,.31.Oct
0x00b0: 2032 3031 3420 3139 3a34 393a 3236 2047 .2014.19:49:26.G
0x00c0: 4d54 0d0a 436f 6e6e 6563 7469 6f6e 3a20 MT..Connection:.
0x00d0: 636c 6f73 650d 0a0d 0a63 0d0a 696e 7661 close....c..inva
0x00e0: 696c 6420 4349 4452 0d0a ild.CIDR..

Rougly translated to "Invalid CIDR."

[1] https://review.openstack.org/#/c/121407/