Add script for launching unit tests with fail fast enabled

diff --git a/contrib/test_failfast b/contrib/test_failfast
new file mode 100755 (executable)
index 0000000..c5dcaa3
--- /dev/null
+++ b/contrib/test_failfast
@@ -0,0 +1,4 @@
+#!/bin/sh
+
+cd "$(dirname "$0")/../gram/test"
+python -m unittest -f