Add sample configs to distribution

[Ed McDonagh]

From https://bitbucket.org/openrem/openrem/commits/e4fc150166d7eb17afe420c5d1d34ac8#comment-6594750 and also refs #660 and #651

Make the linux configs available inside the distribution, instead of having to copy-paste all the time, would be hand, e.g.

• openrem-server,
• gunicorn-openrem.service,
• celery.conf,
• celery-openrem.service,
• openrem_orthanc_config.lua

The stuff folder isn't in the distribution, so it would have to be in a new folder alongside remapp and openremproject. Maybe sample-config

Also relates to ref #657, though the sample local_settings files would be in the openremproject folder as at present.