Add new script for gate jobs

This script will run scenario specified by $RALLY_SCENARIO
environment variable.

Also tags now supported. Tags are stand for modifying
deployment or environment somehow.

Currently implemented only "v3" tag. This tag is changing
deployment endpoints to use keystone v3 protocol.

For example we want to run two scenarios: one for keysone v2
and one for v3. Then we need to create two files:

my-rally.yaml    # will be run vs keystone v2 (v2 is used by default)
my-rally_v3.yaml # will be run vs keystone v3

And export $RALLY_SCENARIO=my-rally.yaml

Change-Id: I44d1788e3892be59afbf8eaecb5d3e3b995fc3a8

rally-jobs/rally-mos.yaml

@@ -0,0 +1,89 @@
+---
+
+  KeystoneBasic.create_user:
+    -
+      args:
+        name_length: 10
+      runner:
+        type: "constant"
+        times: 8
+        concurrency: 1
+      sla:
+        failure_rate:
+          max: 0
+
+  KeystoneBasic.create_delete_user:
+    -
+      args:
+        name_length: 10
+      runner:
+        type: "constant"
+        times: 8
+        concurrency: 1
+      sla:
+        failure_rate:
+          max: 0
+
+  KeystoneBasic.create_and_list_tenants:
+    -
+      args:
+        name_length: 10
+      runner:
+        type: "constant"
+        times: 1
+        concurrency: 1
+      sla:
+        failure_rate:
+          max: 0
+
+  KeystoneBasic.create_and_list_users:
+    -
+      args:
+        name_length: 10
+      runner:
+        type: "constant"
+        times: 1
+        concurrency: 1
+      sla:
+        failure_rate:
+          max: 0
+
+  KeystoneBasic.create_tenant:
+    -
+      args:
+        name_length: 10
+      runner:
+        type: "constant"
+        times: 1
+        concurrency: 1
+      sla:
+        failure_rate:
+          max: 0
+
+  KeystoneBasic.create_tenant_with_users:
+    -
+      args:
+        name_length: 10
+        users_per_tenant: 10
+      runner:
+        type: "constant"
+        times: 1
+        concurrency: 1
+      context:
+        users:
+          tenants: 3
+      sla:
+        failure_rate:
+          max: 0
+
+  KeystoneBasic.create_delete_user:
+    -
+      args:
+        name_length: 10
+      runner:
+        type: "constant"
+        times: 1
+        concurrency: 1
+      sla:
+        failure_rate:
+          max: 0