Toil/CWL Support

[cbmckni]

Slurm-in-docker should provide support for CWL workflows. This can be implemented by installing the Toil workflow manager. The standard installation is done through Pip, and building from source has requirements that prevent the creation of an LMod module.

I will initially bake in both Python-pip and Toil into the controller image, other options can be discussed in the future.