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/PackageReceiver.java b/src/com/android/documentsui/PackageReceiver.java
index 8789171..ec6014a 100644
--- a/src/com/android/documentsui/PackageReceiver.java
+++ b/src/com/android/documentsui/PackageReceiver.java
@@ -22,6 +22,8 @@
 import android.content.Intent;
 import android.net.Uri;
 
+import com.android.documentsui.picker.LastAccessedProvider;
+
 /**
  * Clean up {@link LastAccessedProvider} and {@link LocalPreferences} when packages are removed.
  */