Adds verfication for Bootable Volume

This submission is to verify the response body of Bootable Volume.
To do so, added required assertions in "test_volumes_get.py"
test script located at ./api/volume and also required modifications
are done in get_volume, list_volumes, list_volumes_with_detail
methods of volumes_client.py(XML)

Implements blueprint: cinder-grizzly1-blueprints-implementation

Change-Id: Id8ac81e268abde1df8d11055079e13e67d4e7ae1
diff --git a/tempest/api/volume/test_volumes_get.py b/tempest/api/volume/test_volumes_get.py
index 2e90f16..e5e350e 100644
--- a/tempest/api/volume/test_volumes_get.py
+++ b/tempest/api/volume/test_volumes_get.py
@@ -68,6 +68,10 @@
                          fetched_volume['metadata'],
                          'The fetched Volume is different '
                          'from the created Volume')
+        if 'imageRef' in kwargs:
+            self.assertEqual(fetched_volume['bootable'], True)
+        if 'imageRef' not in kwargs:
+            self.assertEqual(fetched_volume['bootable'], False)
 
     @attr(type='gate')
     def test_volume_get_metadata_none(self):