Patch simple cache (#131)

* Added test and fixed minor bug

* Added meta files

* Added class comment

* Updated integration test version

* Require Symfony for testing

* Require mockery

Author: Nyholm

composer.json

@@ -36,7 +36,7 @@
     },
     "require-dev": {
         "phpunit/phpunit":         "^4.0 || ^5.1",
-        "cache/integration-tests": "^0.13",
+        "cache/integration-tests": "^0.14",
         "cache/array-adapter":     "^0.5"
     },
     "autoload":    {