Problem using the default image

I'm not sure if I'm doing something wrong, but I'm utterly failing to use the default Slurm image to do some basic MPI.

I've stood up a simple cyclecloud-slurm setup with the default image (Cycle CentOS 7) for all node types.

I can run a simple single node MPI job as long as I use Intel MPI:

srun -n2 mpirun ./hello

That works fine.

But as soon as I try to use more than one node, I get all sorts of infiniband related error messages.

If I try to use a machinetype that supports Infiniband I end up with no functioning MPI at all, as it appears to not get installed.

Try even a single node MPI test with OpenMPI and I get errors possibly related to hostname issues:

```
--------------------------------------------------------------------------
ORTE has lost communication with a remote daemon.

HNP daemon : [[22239,0],0] on node ip-0A000406
Remote daemon: [[22239,0],1] on node hpc-1
```

Looks like OpenMPI is working with the Slurm node name (hpc-1) rather than that actual hostname (ip-0A000406), and then possibly getting upset as a result?

If I've missed something really obvious, please do point it out :)

Thanks,

John