#3 Master selection

[Kazuyuki Shudo]

One Host is in charge of master when Hosts run a
master-worker type application. On current P3, a Host
takes charge of master if the Host is invoked by the
mc-master script instead of mc-host script. The master
is choosen randomly if ther is no Host invoked by the
mc-master script.

The current algorithm described above is not very smart
and should be improved. At least a job-submitting user
should be able to choose a Host as master using Controller.