Update to test scripts to work with both ModemManager and Cromo

test/mm-poll-signal-strength

 #!/usr/bin/python
 
+# Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
 import re
 import sys
 import time
 
 import dbus
 import mm
 
 INTERFACES = ['interface_1_dbm', 'interface_2_dbm']
 
 TIME = 60
 SAMPLES = TIME * 2
 
 
-manager = mm.ModemManager()
-path = mm.PickOneModem(manager, '')
+(manager, path) = mm.PickOneModem('')
 simple_modem = manager.SimpleModem(path)
 
 strengths = []  # list of lists where list[i] is dbm for interface #i
 start = time.time()
 finish = start + TIME
 
 for i in xrange(SAMPLES):
         next_reading_time = start + i * (float(TIME) / float(SAMPLES))
 
         # Wait for next reading time
@@ skipping 25 matching lines @@
             sum([sample[interface] for sample in strengths]) /
             float(len(strengths)))
 
 output = ['%.1f' % x for x in [start] + means]
 output_string = '\t'.join(output)
 
 print >> sys.stderr, (
     time.strftime('%a, %d %b %Y %H:%M:%S local:  ', time.localtime()) +
     output_string)
 print output_string