We now trigger an event in user_events.js, and we dynamically
build the list of names in pm_list.js by calling out to
people.get_recipients().
We have a few variations of functions that build lists of names
for huddles, which should be cleaned up eventually. They are
called at different times in the code path, so the different
functions, while doing mostly the same thing, start with different
data sources.
Note that this only works for people who are currently logged in.
Folks that log in after you may pick up the old full name from
the message. (I'll address this in a separate commit.)