Move more classes to more specific locations.

Moved .model classes to .base.
Deleted some unused classes.
Moved functional tests into a new .funcitonal package.
Followup to 1450250.

Change-Id: Ic087fe4a014d9179fab3dc6f833aaf73373f9452
diff --git a/src/com/android/documentsui/DirectoryLoader.java b/src/com/android/documentsui/DirectoryLoader.java
index b5079fd..8a14e31 100644
--- a/src/com/android/documentsui/DirectoryLoader.java
+++ b/src/com/android/documentsui/DirectoryLoader.java
@@ -29,8 +29,8 @@
 import android.provider.DocumentsContract.Document;
 import android.util.Log;
 
-import com.android.documentsui.model.DocumentInfo;
-import com.android.documentsui.model.RootInfo;
+import com.android.documentsui.base.DocumentInfo;
+import com.android.documentsui.base.RootInfo;
 import com.android.documentsui.sorting.SortModel;
 
 import java.io.FileNotFoundException;