Usage of promises

[duesenfranz]

Would you be OK with usage of promises? A large part of this library has a lot successCB, errorCB etc. that could probably be cleaned up with their usage. They are not stabilized (part of ECMA6), but are included in FF (which seems to be the main target of this lib).
This would probably be a breaking change for the API.

[willyaranda]

I would say YES! but I prefer @lodr to chime in, because I think he wants to help in the project and do a refactor (breaking the API)