Add quota table in PLUMgrid plugin

Quota DB driver is enabled in Neutron by default.
PLUMgrid plugin was missing the "quota" table. It has
been added in this commit.

Fix bug# 1236970

Change-Id: I5170a8be2b412a3bcf1edcacce5574f0073b84d4
Merge "Add quota table in PLUMgrid plugin"