Clean up GPFS setup script

Clean up GPFS setup script

Remove the mknsd.sh and nsd_server_common.bash scripts, merging their
functionaility into the main script.

Separate the logic into functions, and default to calling each
function in turn.  Arguments can be passed to potentially run only
some functions but this is probably pointless.

Clean up a lot of contorted logic for building the GPFS nodes file and
deciding on primary/secondary nodes.  Create all files in the same
directory as the scripts (instead of /tmp) since they should be
available for post-mortem anyway.

Signed-off-by: Martin Schwenke <martin@meltin.net>