Differentiate more clearly between presence type and the show element

Conflicts:
	index.html

Conflicts:
	index.html

Conflicts:
	CHANGES.rst
	converse.js

Also, don't save subscription requesting contacts to cache.

Also, don't fetch vCards in rosterHandler. This could be very expensive for
large rosters, instead we'll fetch them when a user comes online.

Additionally:
It's not feasible to get the current user's fullname from a vCard all the time,
so we still get it from the DOM for now.