Linux walkthrough

https://www.openmicroscopy.org/site/support/omero5-staging/sysadmins/unix/server-linux-walkthrough.html

I've taken the easy way out for now so it can at least be reviewed. I've copied the scripts from https://github.com/manics/omero-install into this repo and added a skeleton sphinx doc.

I'm happy to put the doc into https://github.com/manics/omero-install so it's a standalone repo though if you think that's better in the longer term.

Note there's an example of testing these scripts with Docker https://github.com/manics/omero-install/tree/master/test but this isn't part of the ome-docs repo.