* Unsubscribing
* Incoming subscription requests.

Noticed that it's not necessary to call "unauthorize" when setting
subscription="remove".

Did a bit of renaming and fixed a bug in updateContact where a user wasn't
created when it should have been.

Conflicts:
	converse.js

Fix this by pointing to the tag via a git URL

* Fixed a bug in the process which prevented "to" contacts from being shown as
existing.
* Add "to" or "both" as classes on the contacts to indicate their
subscription status.
* Delete roster handlers in tearDown method to avoid them being registered
multiple times.

Also update changelog and fix some linting errors.

Fixes #360

Adding 'rooms' API

fixes #364

Already testing the first 3 sections of RFC-3921 section 8.2 "User subscribes to contact".

Also, added code to acknowledge a subscription being accepted.
See https://xmpp.org/rfcs/rfc3921.html#substates-ack

Refactor out the code for sending an IQ to add a roster contact.
And then call that from acceptRequest.

Some changes to presenceHandler and handleIncomingSubscriptions to avoid using
strophe.roster as well as to remove duplicate code.

Still part of the refactoring of strophe.roster.

The goal being to be able to remove strophe.roster completely.

updates #359

Fix a timeout bug in chat state notifications

* Update the docs to mention the new ``authentication`` option.
* Update failing tests due to ``prebind`` being replaced with ``authentication``.
* Rename 'manual' value for authentication to 'login' since it's used in both manual and auto cases.

Conflicts:
	converse.js

This caused a bug whereby a chat box would open only on chat state
notifications.

Also refactored the chats.open and chats.get methods so that they now reuse the
same map function and so that chats.get can now return any chat box and not
just already open ones.

Updated the tests to properly test this and updated the docs.

Fix the known bug where a state notification reopens a chat box

Fix the ChatRoomOccupants storage id