Doctor in two units: only one subpage is provided

[lukarenko]

If the doctor is operating in two units, when you try to open the doctor page you get only the first data:

Example:

When you open it, you get:
https://zdravniki.sledilnik.org/sl/gyn/bizjak-tina

As URL is not unique (no ID of institution), we only show first.

Solution is to put ID of institiution in URL (but we would need some persitent ID like ZZZS number)

[lukarenko]

id_inst key is persistent now (based on ZZZS ID) and can be used as key for unique doctor URL.

We should extend URLs in following form:
https://zdravniki.sledilnik.org/sl///<id_inst>

If <id_inst> is not specified, we should fallback to first institution (like already now).

The following URLs should work for the above example:
https://zdravniki.sledilnik.org/sl/gyn/bizjak-tina/789398
https://zdravniki.sledilnik.org/sl/gyn/bizjak-tina/91432
https://zdravniki.sledilnik.org/sl/gyn/bizjak-tina

last one is just redirect to first one.

[lukarenko]

@jalezi done the first part, but not sure if we should bother about redirect as we are pre-release.