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>

src/com/android/messaging/datamodel/DataModel.java

@@ -50,7 +50,6 @@ import com.android.messaging.datamodel.data.SettingsData.SettingsDataListener;
 import com.android.messaging.datamodel.data.SubscriptionListData;
 import com.android.messaging.datamodel.data.VCardContactItemData;
 import com.android.messaging.util.Assert.DoesNotRunOnMainThread;
-import com.android.messaging.util.ConnectivityUtil;
 
 public abstract class DataModel {
     private String mFocusedConversation;
@@ -152,7 +151,5 @@ public abstract class DataModel {
 
     public abstract void onApplicationCreated();
 
-    public abstract ConnectivityUtil getConnectivityUtil();
-
     public abstract SyncManager getSyncManager();
 }