fix remove for MemoryCache when using file backend
fix remove for MemoryCache when using file backend

yacon/koala-framework,yacon/koala-framework,nsams/koala-framework,koala-framework/koala-framework,nsams/koala-framework,kaufmo/koala-framework,koala-framework/koala-framework,kaufmo/koala-framework,kaufmo/koala-framework,nsams/koala-framework,yacon/koala-framework