Saving an expired value should be the same as removing that value (#49)

* Saving an expired value should be the same as removing that value

* Updated tests version

Author: Nyholm

composer.json

@@ -32,7 +32,7 @@
     },
     "require-dev":       {
         "phpunit/phpunit":         "^4.0|^5.1",
-        "cache/integration-tests": "^0.9"
+        "cache/integration-tests": "^0.10"
     },
     "suggest":          {
         "ext-memcached": "The extension required to use this pool."