Check for trailing dot in FQDNs for external master & velum fields.

[bergmannf]

Trailing dots causes errors in velum and dex and should not be used.

Should prevent errors described in bsc#1097175.

@vitoravelino I feel the javascript is really ugly and would be very grateful for some nice pointers!

[ereslibre]

What's the status of this PR?

[MalloZup]

This GitHub PR is unactive since 30. Is this GitHub PR still needed? Please close or update it accordingly. This reminder is autogenerated by https://github.com/MalloZup/blacktango