Add the ability to have multiple around_each calls

[runningferret]

Right now a reducer only has the ability to handle a single around_each handler (https://github.com/adomokos/light-service/blob/master/lib/light-service/organizer/with_reducer.rb#L11-L14) It would be awesome if it was possible to have multiple around_each handlers specified, similar to a middleware chain in rack.