Added support for simple cache (#134)

* Added support for SimpleCache

* Added tests

* Bugfix with cloning

* Style fix

* Minor

* Updated integration tests version

* Bugfix

* Allow same keys

* cs

Author: Nyholm

composer.json

@@ -24,7 +24,7 @@
     },
     "require-dev":       {
         "phpunit/phpunit":         "^4.0 || ^5.1",
-        "cache/integration-tests": "^0.14"
+        "cache/integration-tests": "^0.16"
     },
     "autoload":          {
         "psr-4":                 {