Added integration test with the same version

Author: Nyholm

composer.json

@@ -31,8 +31,7 @@
         "league/flysystem":     "^1.0"
     },
     "require-dev":       {
-        "phpunit/phpunit":         "^4.0|^5.1",
-        "cache/integration-tests": "^0.7"
+        "phpunit/phpunit":         "^4.0|^5.1"
     },
     "provide":           {
         "psr/cache-implementation": "^1.0"