Add stub functions for different levels of persistence for software installation

build/config

@@ -1,3 +1,15 @@
 export LC_ALL=C
 export DEBIAN_FRONTEND=noninteractive
-minimal_apt_get_install='apt-get install -y --no-install-recommends'
+
+apt_get_install='apt-get install -y --no-install-recommends'
+minimal_apt_get_install=$apt_get_install
+
+apt_get_install_permanent() {
+    echo $@ >> /build/permanent
+	$apt_get_install "$@"
+}
+
+apt_get_install_temporary() {
+    echo $@ >> /build/temporary
+	$apt_get_install "$@"
+}