[#25] Work towards refactoring the conflict handling into a store responsibility.
[#25] Conflicts are important. Moving resolution handling to its own module.
[#25] For the need to allow multiple conflict handlers, EventListener now allows multiple handlers attached for each type. The onTYPE method is called first, then all the handlers in the order added.
[#25] Implemented conflict event dispatch and handling.
Correct handling of missing event when getting a key which doesn't exist.