Add PlayServices check to generic build

app/src/generic/java/org/tasks/gtasks/PlayServices.java

@@ -1,7 +1,10 @@
 package org.tasks.gtasks;
 
 import android.app.Activity;
+import com.todoroo.astrid.activity.MainActivity;
 import com.todoroo.astrid.gtasks.auth.GtasksLoginActivity;
+import io.reactivex.disposables.Disposable;
+import io.reactivex.disposables.Disposables;
 import javax.inject.Inject;
 import org.tasks.drive.DriveLoginActivity;
 import org.tasks.play.AuthResultHandler;
@@ -30,4 +33,8 @@ public class PlayServices {
 
   public void getDriveAuthToken(
       DriveLoginActivity driveLoginActivity, String a, AuthResultHandler authResultHandler) {}
+
+  public Disposable check(MainActivity mainActivity) {
+    return Disposables.empty();
+  }
 }