Added implementation in common lisp with unit-test

- added the existing implementation in common lisp with system-definition
- added a parachute-unit-test
- added a description for setup and running the unit-tests
- added a description for stubbing and mocking with cl-mock

common-lisp-parachute/tests/package.lisp

@@ -0,0 +1,12 @@
+;;;; package.lisp
+
+(defpackage :gilded-rose-tests
+  (:use :cl :gilded-rose)
+  (:import-from :parachute
+   :define-test
+   :is)
+  (:import-from :cl-mock
+   :with-mocks
+   :answer
+   :call-previous
+   :invocations))