Update message/user channel list with unread counts and colors.

[courtenay]

The RTM stream gets all these messages, may as well put them to work.

• todo: move active channels/users to top of list? lots of users == messages go missing
• adds self-channel back, because it's a valid scratchpad

[courtenay]

.. or is it better to move the channel list to be a table with cells instead of doing regex backflips on the name/counter?