Isolate the current Quorum Vote implementation

As a first step to design and implement the new Quorum Vote API is necessary to isolate the functionalities of the current one, to better understand what we're going to replace/change.

From an high level perspective it means understanding the exact functionalities it's providing to support shared nothing HA, while from an implementation perspective it means to pack the current usage of the classes implementing it (eg QuorumManager) into higher abstraction level domain methods.

This effort won't change the way the current Quorum Vote algorithm works hence it would be nice to make it part of the AMQ code before delivering the new pluggable implementation too.