Add unit test for add_vxlan in test_linux_ip_lib

This patch adds unit tests for the add_vxlan function in the test_linux_ip_lib.py
file.

Fixes bug: 1291974

Change-Id: I0238bedab7a3566aff1115a091ada494a01d2e02
Move test_ovs_lib to tests/unit/agent/linux

Fixes bug 1295846

Change-Id: Ifd3576e9b549361a4baf9cfc2b9301bb45789474
Add missing DB migrations for BSN ML2 plugin

Adds missing database migrations for the Big Switch
ML2 driver and plugin.

Closes-Bug: #1298459
Change-Id: I6a46a53e069353501d85c4c8400f98514d6f0162
Updated from global requirements

Change-Id: I920146bc6ea4eb490f42e1293552536f62949316
Merge "Add unit test for add_vxlan in test_linux_ip_lib"
Merge "Updated from global requirements"
Fix function parsing the kernel version

Change-Id: Id56efb476144a18cd9eb7279bc0f602760a86173
Closes-Bug: #1300808
Merge "Add missing DB migrations for BSN ML2 plugin"
Merge "Fix function parsing the kernel version"
Merge "Move test_ovs_lib to tests/unit/agent/linux"