Merge new test infra changes from bhushana/contrail-fabric-utils for
running new test infra scripts

fab run_sanity task now invokes the run_tests.sh in
contrail-test/ for running sanity/ci-sanity/quick-sanity

Change-Id: I118edce9d704fe0e701133e94a2408546fbf4a2f
Merge "Merge new test infra changes from bhushana/contrail-fabric-utils for running new test infra scripts"