Fix a couple of things I missed in my last checkin.

	* event/program-agent/program-agent.c: Setup of the user
	environment variables wasn't ordered correctly.

	* event/sched/event-sched.c, event/sched/rpc.h,
	event/sched/rpc.cc: Setup the expected user environment variables,
	just like in program-agent.

	* event/sched/simulator-agent.cc: Rename the old feedback data so
	we don't lose it in case the vnode remapping modify fails.

	* xmlrpc/emulabserver.py.in: Add virt_user_environment table data
	to the result of the experiment.metadata method, so the
	event-scheduler can get it.