configuration options misleading - CORE_URL et al. are actually only hostnames, NOT URLs

[skalteis]

Describe the bug
Dear Cytomine-Team,

as of now, I think the configuration file is a bit misleading: The shell variables, that get passed to the containers to set up the different hosts are named "CORE_URL", etc. while actually not allowing any URL syntax at all. They are hostnames, not URLs.
It would be very helpful for people just starting out (and trying to switch the entire setup to TLS...) to clarify/rename these vars to CORE_HOST et al..

Thank you for the work on this great project and best regards
Simon