Merchant Missions

Adds 
1.  Clear the back bay of zombies
2.  Investigate missing caravan
3.  Acquire atomic battery mods

Would have held off for the other mission sets but this ads a number of changes including support for assassinate missions and basic increase in faction rep as you complete missions.  The site is generated during mission start so it can be in well known/traveled areas.

Known Issues:
-The current item bug means that you shouldn't try to pickup items when you kill the npc bandits.
-Don't ask the merchant to teach you anything, I'll disable that since he needs to be next to you.
-The proximity check for the ambush site doesn't stay in the current world map which can cause the npcs to not spawn, seems pretty rare though.

When I get the Old Guard missions up I'll change the bandit weapons to actually be mostly significant.
In theory, the bandits are only hostile because of your faction relation to them.  So if you can increase Hell's Raiders faction relation (in the future by killing Old Guard/police type npcs) I could potentially add a non-hostile way of solving the situation (large cash sum).