Add Messenger class for posting messages

[fracture91]

Should have a class that you can give a message and it will post it for you. See https://github.com/fracture91/ignpp/blob/2.3.0/content/message.js, but design it less retardedly. Should be able to instantiate one. Maybe subclasses depending on type (Edit, Topic, Reply). Maybe use FormData? Messenger should subclass Model.

Will need a good amount of "research" into mimicking the requests XenForo makes. I think the "keys" are located on the page somewhere now, no need to have that extra step.