Add force external setting

Adds a developer setting that overrides the package's storage
preference. This allows any [non-system] package to be moved
to external storage.

Bug: 22282121
Change-Id: Ie21bc13b1d92fe0972f789a2187e11d2e413f040
diff --git a/res/xml/development_prefs.xml b/res/xml/development_prefs.xml
index 7887f87..ba87860 100644
--- a/res/xml/development_prefs.xml
+++ b/res/xml/development_prefs.xml
@@ -342,6 +342,11 @@
                 android:key="inactive_apps"
                 android:title="@string/inactive_apps_title" />
 
+        <SwitchPreference
+            android:key="force_allow_on_external"
+            android:title="@string/force_allow_on_external"
+            android:summary="@string/force_allow_on_external_summary"/>
+
      </PreferenceCategory>
 
 </PreferenceScreen>