Draft: Add support for building conda-dist envs
See changes to README for description.
TODO:
- Figure out is we should build and host docker images somewhere, rather than instructing users to download Dockerfile.conda-dist and build the image themselves.
- Tests for call.py -- Do we even want call.py? if we always use Skein to launch from conda packed envs, we don't need call.py.
Edited by Ottomata