ReplaceDonutsInChildActions became IgnoreDonutsInChildActions.

Following discussions with @mlidbom, the default behaviour should be to replace donuts in child actions by default. Previous behaviour can be restored by applying the new option globally or locally (ref: #7).
See https://github.com/moonpyk/mvcdonutcaching/commit/2fad58186b2dd82784dc9f35d4dcf18b87f3a9db for discussion.