Bugfixes for Exchange Objectives

-Will no longer be assigned to latejoiners
-Objective description will report the other agent's real_name
-Objective description will report what job the other agent is
-Objective description will properly rename itself if the other agent is renamed (e.g. clowns, mimes)
-Explanation text made more noticeable
-Cleaned up the code a bit

Fixes #3927
Fixes #3786
I'm still getting confused players not knowing what to do since the message is easily lost among the rest of the traitor text. It's just to make it more visible. 

Sent from my iPhone

> On Jun 15, 2014, at 7:16 AM, "Remie Richards" <notifications@github.com> wrote:
> 
> In code/game/gamemodes/traitor/traitor.dm:
> 
> > \ No newline at end of file
> > +
> > +	var/where = "At your feet"
> > +	var/equipped_slot = mob.equip_in_one_of_slots(folder, slots)
> > +	if (equipped_slot)
> > +		where = "In your [equipped_slot]"
> > +	mob.update_icons()
> > +	spawn(110)
> What even is the point of Delaying the message? The folder has already spawned and the Traitor who get's it will already know what to do with it.
> 
> —
> Reply to this email directly or view it on GitHub.