add test target for stable/grizzly

rename previous grizzly to master and add test target for stable/grizzly.
  rename target for master branch:
    grizzly-gre -> master-gre
    grizzly-vlan -> master-vlan

  add target for stable/grizzly branch:
    grizzly-gre
    grizzly-vlan

to update your jenkins jobs:
  copy grizzly-* to master-* and modify the build script.
    #!/bin/bash
    set -e
    ./update-devstack.sh master-gre
    ./run.sh master-gre

  and modify trigger url of grizzly-*.
    github.com/openstack/quantum/commits/master.atom
    github.com/openstack/nova/commits/master.atom
    -> github.com/openstack/quantum/commits/stable/grizzly.atom
       github.com/openstack/nova/commits/stable/grizzly.atom