Create user to run as non-root

[cmball1]

In reference to this comment: DataBiosphere/topmed-workflows#66 (comment)
In this PR: DataBiosphere/topmed-workflows#66

I wanted to create a PR here to see if we can get the Dockerfile changes integrated into the statgen/alignment image. Running the CWL Workflow in Toil with a Docker container where the user is root causes problems. I modified the Dockerfile to create a user to run as when the Docker Image is launched.

CWL Workflow: https://github.com/DataBiosphere/topmed-workflows/blob/master/aligner/sbg-alignment-cwl/topmed-alignment.cwl

[jonathonl]

This PR seems pretty specific to your environment. Can you achieve the same outcome by running containers with one of the following?

docker run --user `id nobody` statgen/docker-alignment whoami

or

docker run --user $(id `whoami`) statgen/docker-alignment whoami

[cmball1]

@jonathonl It looks like I can make it run as is with a few more input options. Sorry for the delayed response. I'll close this PR. Thanks!