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/LoadRootTask.java b/src/com/android/documentsui/LoadRootTask.java
index c5d359b..1b98ce0 100644
--- a/src/com/android/documentsui/LoadRootTask.java
+++ b/src/com/android/documentsui/LoadRootTask.java
@@ -20,7 +20,8 @@
 import android.provider.DocumentsContract;
 import android.util.Log;
 
-import com.android.documentsui.model.RootInfo;
+import com.android.documentsui.base.PairedTask;
+import com.android.documentsui.base.RootInfo;
 
 final class LoadRootTask extends PairedTask<BaseActivity, Void, RootInfo> {
     private static final String TAG = "RestoreRootTask";