Pyfilesystem fix for AWS

pyfs expects AWS access/secret keys. This prevents it from working with VPC auth in prod. This removes the expectation. See: 

  https://github.com/pmitros/pyfs/commit/96e1922348bfe6d99201b9512a9ed946c87b7e0b

Same fix for pyfs latest worked without issues on sandbox. Imports/exports have a version dependency on pyfs-0.4.0, so test failed. I am waiting on tests to run and on sandbox provisioning to see if this is ready to go.