flag at batch job launch time.

  extend options available to user. User provided options are forwarded to 
  slurmd via generic job_options list associated with task launch request.

Permit batch jobs to be requeued, scontrol requeue <jobid>

* Fix for slurmctld behaviour when environment is NULL on batch script launch
* Move client (srun) IO code into the API in preparation for adding
  an API call for launching a normal parallel job step.
* Rename SLURM_CRED_SIGLEN back to SLURM_IO_KEY_SIZE, but put it in a better
  header.

updated return codes from slurm_send_recv_rc_msg_only_one and slurm_send_recv_contoller_rc_msg to either 0 or -1 and added error checking to api/signal.c

call to slurm_open_controller_conn

    job as CANCELLED rather than COMPLETED and change its start and end time
    to that time.

of running autogen.sh.  Now it is no longer necessary to run "./autogen.sh"
after checking out SLURM; you can go straight to "./configure".

correct pointer to MPICH2 site, 
use different prompt within srun --allocate for clarity.