Add detach_volume request method for block storage service.

lib/fog/hp/requests/compute/detach_volume.rb

@@ -0,0 +1,47 @@
+module Fog
+  module Compute
+    class HP
+      class Real
+
+        # Detach a block storage volume from an existing server
+        #
+        # ==== Parameters
+        # * server_id<~Integer> - Id of server to attach the volume to
+        # * volume_id<~Integer> - Id of the volume to be attached to the server
+        #
+        # ==== Returns
+        # * response<~Excon::Response>:
+        #   * body: Empty
+        def detach_volume(server_id, volume_id)
+          response = request(
+            :expects  => 202,
+            :method   => 'DELETE',
+            :path     => "servers/#{server_id}/os-volume_attachments/#{volume_id}"
+          )
+          response
+        end
+
+      end
+
+      class Mock  # :nodoc:all
+
+        def detach_volume(server_id, volume_id)
+          response = Excon::Response.new
+          if server = self.data[:servers][server_id]
+            if server['volumeAttachments'] && server['volumeAttachments'].select {|v| v['volumeId'] == volume_id}
+              data = server['volumeAttachments'].reject {|v| v['volumeId'] == volume_id}
+              self.data[:servers][server_id]['volumeAttachments'] = data
+              response.status = 202
+            else
+              raise Fog::Compute::HP::NotFound
+            end
+          else
+            raise Fog::Compute::HP::NotFound
+          end
+          response
+        end
+
+      end
+    end
+  end
+end