management_url not set by authenticate method

Fixes Bug 1109243.
If management_url not set, raise UnAuthorized exception,
otherwise url chaining methods fail and cause NoneType
exceptions.

Change-Id: I19e87a5dcfcf93b4fa1d423bd99de352679fa16d

novaclient/client.py

@@ -377,6 +377,8 @@ class HTTPClient(object):
 
         if self.bypass_url:
             self.set_management_url(self.bypass_url)
+        elif not self.management_url:
+            raise exceptions.Unauthorized('Nova Client')
 
         # Store the token/mgmt url in the keyring for later requests.
         if has_keyring and self.os_cache: