Don't throw ValueError for invalid volume id

If a user runs something like "cinder-manage volume delete a1234",
a ValueError is thrown because it fails to cast to int.
Catch this and treat the parameter as an id which will result in a
later VolumeNotFound error rather than breaking this way.

Change-Id: I95a9b9d7628cebe4b6d855ea925b0ad3a5f1c4c4

bin/cinder-manage

@@ -108,7 +108,10 @@ def param2id(object_id):
         # FIXME(ja): mapping occurs in nova?
         pass
     else:
-        return int(object_id)
+        try:
+            return int(object_id)
+        except ValueError:
+            return object_id
 
 
 class ShellCommands(object):