Avoid an extra database query in schedule_snat_router

bind_snat_servicenode already knows the chosen_agent.  By waiting
until after it is called, we can use it to avoid another db query.

Closes-bug: #1353266
Closes-bug: #1356639
Co-Authored-By: Swaminathan Vasudevan <swaminathan.vasudevan@hp.com>

Change-Id: Iba5668b2717e188d5289ede982bfc1b46f4eeb5b
Tunnel ID range validation for VXLAN/GRE networks

Currently, there is no check which validates the values of
tunnel range for VXLAN/GRE networks. The VXLAN VNI is 24 bit
which have range between 1 to 2^24 - 1. Similarly, GRE key field
is 32 bit which have range between 1 to 2^32 - 1.

Closes-Bug: #1306488

Co-Authored-By: romilg romilg@hp.com

Change-Id: Idb3d0f41166df589a1e90394d9319901b5f9b439
Merge "Tunnel ID range validation for VXLAN/GRE networks"
Merge "Avoid an extra database query in schedule_snat_router"
Merge branch 'master' of https://github.com/openstack/quantum