Fix Venado submission script issue

[brryan]

Background

@111-1000 noticed that env/bash is no longer working when called from submission scripts. This is due to #13's use of HOSTNAME which is not the same as HOST on venado backend nodes; we want to switch this to HOST.

Description of Changes

• Switch HOST to HOSTNAME on venado backend
• Slightly more modern venado environment (still not working across multiple ranks on venado GPUs)

Checklist

• New features are documented
• Tests added for bug fixes and new features
• (@lanl.gov employees) Update copyright on changed files