added script to test-checkout the skeleton repo

Author: richard-ejem

.gitattributes

@@ -2,3 +2,4 @@
 /tests/skeleton-test.sh export-ignore
 /.travis.yml export-ignore
 /license.md export-ignore
+/bin/checkout.sh export-ignore

bin/checkout.sh

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+
+dir=${1-instante-app}
+mkdir "$dir"
+git --git-dir "$(dirname "$0")/../.git" --work-tree "$dir" checkout-index -a -f