Add test binstub

Author: dhh

CONTRIBUTING.md

@@ -33,13 +33,7 @@ git checkout -b my-feature-branch
 
 #### Bundle Install and Test
 
-Ensure that you can build the project and run tests.
-
-```
-bundle install
-appraisal install
-appraisal rake test
-```
+Ensure that you can build the project and run tests using `bin/test`.
 
 #### Write Tests
 

bin/test

@@ -0,0 +1,6 @@
+#!/bin/env bash
+set -e
+
+bundle install
+appraisal install
+appraisal rake test