All delegate methods should be forked out inside the cache Worker

[whitfin]

Right now there's a blend of delegates in that some delegate inside the Worker (expire_at/persist) and some delegate in Cachex (decr).

It should be ensured that all of these delegates do take place inside the Worker. It adds a bit of extra and arguably redundant code, but it allows the hook notifications to contain the correct function. As it stands right now, if you call Cachex.decr(:my_cache, "key") your notification becomes { :incr, "key" }, which totally sucks (and is why this is marked as a bug). Anyone listening for decr calls will just never get them.

Alternatively, perhaps we could add a recognisable :from or :via to all the worker functions, so if you call something like Cachex.incr(:my_cache, "key", via: :decr), it notifies using { :decr, "key" } (overriding the function name).