Missing requirement: `gcsfs`

[sjfleming]

This line imports gcsfs, but it is not in requirements.txt:

cromshell/src/cromshell/logs/command.py

Line 5 in 634803e

import gcsfs

This makes a pip install fail when I try

git clone https://github.com/broadinstitute/cromshell.git
cd cromshell
git checkout cromshell_2.0
pip install .