Restoring openstack_release option
Restoring openstack_release option

This patch restores openstack_release option in globals.yml,
change version to 2.0.0 to match Mitaka.

Closes-Bug: 1565353

Change-Id: I00342d1f52360e7d2c38b4467dc0b4049b7191dd

negronjl/kolla,negronjl/kolla,negronjl/kolla