Add begin_detaching and roll_detaching functions

Fixes bug #1004382

If nova call nova.volume.cinder.API.begin_detaching and
nova.volume.cinder.API.roll_detaching, it need python_cinderclient
support the functions.

Change-Id: If5d00a7f7991d78243e76a6e22031c185caee80a

cinderclient/v1/volumes.py

@@ -61,6 +61,18 @@ def unreserve(self, volume):
         """
         return self.manager.unreserve(self)
 
+    def begin_detaching(self, volume):
+        """
+        Begin detaching volume.
+        """
+        return self.manager.begin_detaching(self)
+
+    def roll_detaching(self, volume):
+        """
+        Roll detaching volume.
+        """
+        return self.manager.roll_detaching(self)
+
     def initialize_connection(self, volume, connector):
         """
         Initialize a volume connection.
@@ -267,6 +279,24 @@ def unreserve(self, volume):
         """
         return self._action('os-unreserve', volume)
 
+    def begin_detaching(self, volume):
+        """
+        Begin detaching this volume.
+
+        :param volume: The :class:`Volume` (or its ID)
+                       you would like to detach.
+        """
+        return self._action('os-begin_detaching', volume)
+
+    def roll_detaching(self, volume):
+        """
+        Roll detaching this volume.
+
+        :param volume: The :class:`Volume` (or its ID)
+                       you would like to roll detaching.
+        """
+        return self._action('os-roll_detaching', volume)
+
     def initialize_connection(self, volume, connector):
         """
         Initialize a volume connection.

tests/v1/test_volumes.py

@@ -41,6 +41,16 @@ def test_unreserve(self):
         cs.volumes.reserve(v)
         cs.assert_called('POST', '/volumes/1234/action')
 
+    def test_begin_detaching(self):
+        v = cs.volumes.get('1234')
+        cs.volumes.reserve(v)
+        cs.assert_called('POST', '/volumes/1234/action')
+
+    def test_roll_detaching(self):
+        v = cs.volumes.get('1234')
+        cs.volumes.reserve(v)
+        cs.assert_called('POST', '/volumes/1234/action')
+
     def test_initialize_connection(self):
         v = cs.volumes.get('1234')
         cs.volumes.initialize_connection(v, {})