shill: On Service::Connect, connect the modem device to the network.

Also, uncouple the DBusProperties signal callbacks from Modem to make the proxy
implementation more consistent with the other proxies.

BUG=chromium-os:18727
TEST=unit tests

Change-Id: Icdddea8d2a30803150f2a159fdc5a719e960f95d
Reviewed-on: http://gerrit.chromium.org/gerrit/5444
Tested-by: Darin Petkov <petkov@chromium.org>
Reviewed-by: Chris Masone <cmasone@chromium.org>
diff --git a/mock_modem_simple_proxy.h b/mock_modem_simple_proxy.h
index f0ba0a2..b5877df 100644
--- a/mock_modem_simple_proxy.h
+++ b/mock_modem_simple_proxy.h
@@ -14,6 +14,7 @@
 class MockModemSimpleProxy : public ModemSimpleProxyInterface {
  public:
   MOCK_METHOD0(GetStatus, DBusPropertiesMap());
+  MOCK_METHOD1(Connect, void(const DBusPropertiesMap &properties));
 };
 
 }  // namespace shill