Add various plugin manager

Hi,

This PR adds two plugin managers: one for hydrators and one for input filters. It also fixes a bug for the Serializer adapter (I introduced another way than adding all the listener in the ModuleManagerFactory but in fact my approach did not work at all, so until we find a cleanest way, I've just added another new listenenr in the ModuleManagerFactory).

Those plugin managers would be really useful for one module I'm working on, and this continue to make the framework more uniform with same logic.

I'd like this to be merged for 2.2 if that's possible =).

(PS: for ZF 3, we'd like to find a better solution, I think that adding so much listeners will lower performance, at some point...)