Move stuff into commands and write tests.

testing/resources/failing_hook_repo/bin/hook.sh

@@ -0,0 +1,6 @@
+#!/usr/bin/env bash
+
+
+echo 'Fail'
+echo $@
+exit 1

testing/resources/failing_hook_repo/hooks.yaml

@@ -0,0 +1,4 @@
+-   id: failing_hook
+    name: Failing hook
+    entry: bin/hook.sh
+    language: script

testing/resources/prints_cwd_repo/prints_cwd/main.py

@@ -1,5 +0,0 @@
-import os
-
-def func():
-    print os.getcwd()
-    return 0