Switch to Docker build environment

[ackagel]

Installing and using conda might be unintuitive to user-base. We should change the environment manager to Docker. There should also be instructions for putting dependencies into a .yml for Linux users (or a separate Linux fork w/ the conda environment yml, along with instructions for installation).

[mapazarr]

Rather than switching, I'd prefer if we could support both workflows in parallel. I wonder if we could define the package dependencies only once and make it work for both installation types: docker and conda.

[mapazarr]

Sorry, wrong button :-)

[ackagel]

That could work. We could use a bash script which takes a docker/conda flag and builds/installs the preferred environment. This might mean having using another script to start/activate the environment, but we could maybe package it all into one script with two 'modes' (install and run), which takes a docker/conda flag.