Fix users loaded in GuildCreate missing presence information

The presence data comes sep. from the users info here, so we need to
load it.

disco/state.py

@@ -186,6 +186,9 @@ class State(object):
         for member in six.itervalues(event.guild.members):
             self.users[member.user.id] = member.user
 
+        for presence in event.presences:
+            self.users[presence.user.id].presence = presence
+
         for voice_state in six.itervalues(event.guild.voice_states):
             self.voice_states[voice_state.session_id] = voice_state