Agents can shut down gracefully

commit 2e5cfeef1282af75ce33522c1fd0a97f5d87a4a2
Author: Michael Marconi <michael@modeltwozero.com>
Date:   Sun Jan 20 17:03:05 2013 +0000

    Agent shutdown handled and tested

commit 584ab22eaf5c414c41a1db9513b86c169f2c10ff
Author: Michael Marconi <michael@modeltwozero.com>
Date:   Sun Jan 20 16:12:40 2013 +0000

    WIP

commit edfa3d7e1e0c4993a193dfa3c9d29ce6f56d4984
Author: Michael Marconi <michael@modeltwozero.com>
Date:   Sun Jan 20 15:53:20 2013 +0000

    WIP

    - Scheduler keeps track of agents in the form of path strings, rather than ActorRefs
    - Scheduler now monitors remote agents for graceful shut down