agent to exit. rc.progagent now loops, restarting the program agent,
but first getting new copies of the agent list and the environment
from tmcd.

Note that this conflicts slightly with the pa-wrapper used on plab
nodes, which also loops. I think we can just get rid of pa-wrapper
now, along with a slight change to rc.progagent. I'm gonna let Kirk
comment on this.

Need new images ...