some updates for bluegene documentation for scontrol and troubleshooting how to down ionodes in a bluegene system without a block there.

change mpich-gm plugin name to mpichgm (there was previously 
some inconsistent naming).

the leak, so it does not grow).

changed slurm_send_recv_controller_rc_msg to handle all rm messages instead of just SLURM_RC_MESSAGE

slurm_send_recv_controller_msg() rather than use it's own 
logic. This provides much better support for the backup 
controller during the fail-over period.

to reduce logging load.

RPC) a parameter, effectively raise the time from 1 to 5 mins.

    tests, patch.1.2.0-pre11.070111.plane from Dan Palermo (HP).