Add image arg for creating volume from image

This change adds image arg to next scenarios: create_volume,
create_and_delete_volume, create_and_list_volume.
Add nullable arg to image_exists for specify image require.

Change-Id: Idb2f80efa24d6f721bbdafc4644afc68d59552ac

rally-jobs/rally-neutron.yaml

@@ -503,6 +503,22 @@
       sla:
         failure_rate:
           max: 0
+    -
+      args:
+        size: 1
+        image:
+          name: {{image_name}}
+      runner:
+        type: "constant"
+        times: 3
+        concurrency: 3
+      context:
+        users:
+          tenants: 2
+          users_per_tenant: 2
+      sla:
+        failure_rate:
+          max: 0
 
   CinderVolumes.create_and_list_volume:
     -
@@ -520,6 +536,23 @@
       sla:
         failure_rate:
           max: 0
+    -
+      args:
+        size: 1
+        detailed: True
+        image:
+          name: {{image_name}}
+      runner:
+        type: "constant"
+        times: 3
+        concurrency: 3
+      context:
+        users:
+          tenants: 1
+          users_per_tenant: 1
+      sla:
+        failure_rate:
+          max: 0
 
   CinderVolumes.list_volumes:
     -
@@ -555,6 +588,22 @@
       sla:
         failure_rate:
           max: 0
+    -
+      args:
+        size: 1
+        image:
+          name: {{image_name}}
+      runner:
+        type: "constant"
+        times: 2
+        concurrency: 2
+      context:
+        users:
+          tenants: 2
+          users_per_tenant: 2
+      sla:
+        failure_rate:
+          max: 0
 
   CinderVolumes.create_and_extend_volume:
     -

samples/tasks/scenarios/cinder/create-from-image-and-delete-volume.json

@@ -0,0 +1,23 @@
+{
+    "CinderVolumes.create_and_delete_volume": [
+        {
+            "args": {
+                "size": 1,
+                "image": {
+                    "name": "^cirros.*uec$"
+                }
+            },
+            "runner": {
+                "type": "constant",
+                "times": 2,
+                "concurrency": 2
+            },
+            "context": {
+                "users": {
+                    "tenants": 2,
+                    "users_per_tenant": 2
+                }
+            }
+        }
+    ]
+}

samples/tasks/scenarios/cinder/create-from-image-and-delete-volume.yaml

@@ -0,0 +1,15 @@
+---
+  CinderVolumes.create_and_delete_volume:
+    -
+      args:
+        size: 1
+        image:
+            name: "^cirros.*uec$"
+      runner:
+        type: "constant"
+        times: 2
+        concurrency: 2
+      context:
+        users:
+          tenants: 2
+          users_per_tenant: 2