Move config file from agent to supervisor

Move config file from agent to supervisor.  @bernerdschaefer 
That was remarkably undocumented.  I've changed it.  It works for our case, but with a weirdly with sorta-useful but with bad failure characteristics sort of way:

vagrant@harpoon:/tmp$ ./argsout --a=a -- e c --d
--a == "a", flag.Args() == [e c --d]

vagrant@harpoon:/tmp$ ./argsout --a=a e -- c --d
--a == "a", flag.Args() == [e -- c --d]