Load only unique dictionary words

- Move UserDictionarySettings to sub package
- Convert cursor to loader

Fix: 22058788
Test: robotests

Change-Id: I1e8828abee58362b815abc210c044b678bf9d578

src/com/android/settings/inputmethod/UserDictionaryAddWordContents.java

@@ -27,7 +27,6 @@ import android.view.View;
 import android.widget.EditText;
 
 import com.android.settings.R;
-import com.android.settings.UserDictionarySettings;
 import com.android.settings.Utils;
 
 import java.util.ArrayList;