Verbose mode

[JanPalasek]

Hello. Today I spend a lot of time debugging why my conda environment creation process gets stuck. I found the answer in the end but it pointed out a problem to me:

• Conda environment creation process has no logs.

I suspect that this problem is more wide-spread in metaflow. This could be imo solved with some kind of verbosity settings. There could be an option --verbose=0 (default) up-to --verbose=10. With these verbosity setting, some logs could be printed out, like e.g. which conda command is currently running.

This would greatly improve the readability and also patience of the "users". If you are creating 5 environment and you don't see anything for 10 minutes, you might end up the process abruptly (which could leave mf_env-creation.lock file and then it's never going to work again until we delete the file).