scenario job improvements

1. our scripts no longer accept engine as option.
2. introduced dsvm-scenario-rc script which can
be used to source important variables before running gate
hooks. that makes job more flexible to config changes.

Change-Id: I84e908842c5bd1e447837eb7c2db68290bd4c88c

tools/gate/scenario/commons

@@ -16,10 +16,8 @@
 # limitations under the License.
 
 export NETWORK=${1:-neutron}
-export ENGINE=${2:-heat}
 export IS_TRANSIENT=true
 export AUTO_SECURITY_GROUP=true
-
 # Normalize network name
 if [[ $NETWORK == nova* ]]; then
     export NETWORK="nova-network"

tools/gate/scenario/dsvm-scenario-rc

@@ -0,0 +1,19 @@
+export DEVSTACK_LOCAL_CONFIG="enable_plugin sahara git://git.openstack.org/openstack/sahara"
+export DEVSTACK_LOCAL_CONFIG+=$'\n'"enable_plugin ceilometer git://git.openstack.org/openstack/ceilometer"
+export DEVSTACK_LOCAL_CONFIG+=$'\n'"enable_plugin heat git://git.openstack.org/openstack/heat"
+export DEVSTACK_GATE_TEMPEST=0
+export DEVSTACK_GATE_EXERCISES=0
+export DEVSTACK_GATE_INSTALL_TESTONLY=1
+export KEEP_LOCALRC=1
+export PROJECTS="openstack/sahara-tests $PROJECTS"
+
+if [ $SAHARA_SCENARIO_GATE_PROJECT == "python-saharaclient" ] ; then
+    export PROJECTS="openstack/python-saharaclient $PROJECTS"
+    export DEVSTACK_PROJECT_FROM_GIT=python-saharaclient
+fi
+
+if [ $SAHARA_SCENARIO_GATE_NETWORK == "nova" ] ; then
+    export DEVSTACK_GATE_NEUTRON=0
+else
+    export DEVSTACK_GATE_NEUTRON=1
+fi