Add Ceilometer list samples

This scenario covers ceilometer "sample-list"

Change-Id: I50c5f957e67a176130d13ac39d23c9eaabee8ee6

rally-jobs/rally.yaml

@@ -296,6 +296,20 @@
         failure_rate:
           max: 0
 
+  CeilometerSamples.list_samples:
+    -
+      runner:
+        type: "constant"
+        times: 10
+        concurrency: 10
+      context:
+        users:
+          tenants: 1
+          users_per_tenant: 1
+      sla:
+        failure_rate:
+          max: 0
+
   Dummy.dummy:
     -
       args:

samples/tasks/scenarios/ceilometer/list-samples.json

@@ -0,0 +1,17 @@
+{
+    "CeilometerSamples.list_samples": [
+        {
+            "runner": {
+                "type": "constant",
+                "times": 10,
+                "concurrency": 2
+            },
+            "context": {
+                "users": {
+                    "tenants": 2,
+                    "users_per_tenant": 2
+                }
+            }
+        }
+    ]
+}

samples/tasks/scenarios/ceilometer/list-samples.yaml

@@ -0,0 +1,11 @@
+---
+    CeilometerSamples.list_samples:
+     -
+       runner:
+         type: "constant"
+         times: 10
+         concurrency: 2
+       context:
+         users:
+           tenants: 2
+           users_per_tenant: 2

tests/unit/fakes.py

@@ -763,6 +763,9 @@ class FakeSampleManager(FakeManager):
         sample = FakeSample(self, **kwargs)
         return [self._cache(sample)]
 
+    def list(self):
+        return ["fake-samples"]
+
 
 class FakeMeterManager(FakeManager):