Add lua plugin for SLURM integration

[dsikich]

A SLURM SPANK lua plugin that adds an option to SLURM called unifycr. Using this option starts and stops the unifycr daemon as the user at job startup and termination.

This also makes the assumption currently that 'unifycrd' is installed in a default system path. The SPANK functions such as task_init and task_exit only run as the user running the job in a remote context.

Plugin still needs to be tested (in progress).

[MichaelBrim]

@dsikich I noticed -alloc_flags was still used in the README. Does srun/salloc really have that flag too? I thought it was specific to LSF's bsub.

[dsikich]

@MichaelBrim I don't think so, I started with your README for lsf, and missed deleting that.

[dsikich]

@MichaelBrim Thanks for catching the alloc_flags in the README.md.. it's been updated/removed.

[CamStan]

Creating an issue to pick this up in the future.