Add basic test for requesting roster
This namespace is unnecessary, Strophe adds it
We can send a builder
Extract a test helper module
Create a main roster
Store roster items in main roster
Request our roster when we connect, before sending initial presence

According to http://xmpp.org/rfcs/rfc6121.html#roster-login
Emit events when the roster is fetched/updated
Ensure Contact tests run
Basic implementation of aggregate presence
Aggregate presence should use highest priority resource
Aggregate status should resolve resource priority ties
Permit bootstrapping roster from cache (roster versioning)
Ensure Contact model is included in the build
Emit a different event when roster is loaded from cache
We're not ready to send initial presence until we've received (and processed) our roster
Make Contact compatible with ChatUser in a bunch of situations
Include roster in loaded/fetched events
No need to inject a connection
Properly namespace events

See #224