general ansible cleanup

initially noticed while bringing in the new roles

DCM user/group/uid/gid needs better organization
check OS version for dependencies (vs currently just checking distributions and assuming it's enough for me)
- rq config needs to go from hardcoded files to templates/variables in case of deployment path changes
judging from initial feedback from pdurbin; system config section of readme is probably unclear. readme needs redoing anyhow.

sbgrid / data-capture-module