added missing isotime method from utils

nova/utils.py

@@ -22,13 +22,14 @@
 System-level utilities and helper functions.
 """
 
-import logging
-import socket
-import sys
-import os.path
+import datetime
 import inspect
-import subprocess
+import logging
+import os.path
 import random
+import socket
+import subprocess
+import sys
 
 from nova import flags
 
@@ -114,3 +115,8 @@ def get_my_ip():
     (addr, port) = csock.getsockname()
     csock.close()
     return addr
+
+def isotime(at=None):
+    if not at:
+        at = datetime.utcnow()
+    return at.strftime("%Y-%m-%dT%H:%M:%SZ")