ProcessPendingMessagesAction works based on subscriptions

PorcessPendingMessagesAction queues one message for sending/downloading
associated with a subscription triggering current action at a time. And
the ConnectivityUtil also works based on subscriptions so that pending
messages can be processed regardless of other phones' state in multi-sim
case.

It includes cleanup code as well.

Test: Manual

Change-Id: Id6b4f4a0aa6a3291e7a4d8a5d3f0fbb9db3c5b86
Signed-off-by: Taesu Lee <taesu82.lee@samsung.com>

tests/src/com/android/messaging/datamodel/DataModelTest.java

@@ -35,10 +35,10 @@ public class DataModelTest extends BugleTestCase {
 
     @Override
     protected void setUp() throws Exception {
-      super.setUp();
-      dataModel = new DataModelImpl(getTestContext());
-      FakeFactory.register(mContext)
-              .withDataModel(dataModel);
+        super.setUp();
+        FakeFactory factory = FakeFactory.register(mContext);
+        dataModel = new DataModelImpl(getTestContext());
+        factory.withDataModel(dataModel);
     }
 
     @SmallTest