Supporting Univention Corporate Server (UCS) as bistro

Would be nice if UCS is detected as own distribution. Its based on Debian.

ATM the distro script provides:

Linux|4.9.0-14-amd64|amd64|Debian|4.4-7 errata867|vmware|

/etc/issue includes type/role of System and minor version in the first line:

Univention Memberserver 4.4-7:
Univention DC Master 4.4-7:
}}{{Univention DC Backup 4.4-7:

Logos could be found here:
https://www.univention.de/pressedownloads/