Run VAE training on screen when running remotely

[ajlee21]

VAE training on all of SRA data for recount2 is estimated to take ~2.5 days running on my lab machine (CPU). When running remotely, use screen to prevent so that data isn't lost when connection is unstable.

Additional changes to improve the computational efficiency of the simulation can be found in this issue

[dongbohu]

tmux might be a better choice than screen, based on my personal experience. More details at:
https://www.howtogeek.com/671422/how-to-use-tmux-on-linux-and-why-its-better-than-screen/