Compatibility changes to work on RHEL 5 with python 2.4

ipa-admintools/ipa-adduser

@@ -228,7 +228,7 @@ def main():
     # Set the User's password
     if password is not None:
         try:
-            client.modifyPassword(principal, None, password)
+            client.modifyPassword(principal, '', password)
         except ipa.ipaerror.IPAError, e:
             print "User added but setting the password failed."
             print "%s" % (e.message)

ipa-admintools/ipa-passwd

@@ -98,7 +98,7 @@ def main():
 
     try:
         client = ipaclient.IPAClient()
-        client.modifyPassword(principal, None, password)
+        client.modifyPassword(principal, '', password)
     except xmlrpclib.Fault, fault:
         if fault.faultCode == errno.ECONNREFUSED:
             print "The IPA XML-RPC service is not responding."