Add German UnitNames

[keilw]

As German native speaker I'd be happy to add the German translation of the UnitNames resources.

[desruisseaux]

Of course that would be welcome!

Optionally, if you are fine about giving those translations to the Apache Software Foundation, they could also be integrated into Apache SIS (but don't have to of course).

[keilw]

I can, I also have an Apache user with all the contributor agreement, etc. in place.
Does SIS already use Git or still SVN?

[desruisseaux]

SIS is on Git now, on https://gitbox.apache.org/repos/asf?p=sis.git but mirrored on https://github.com/apache/sis. Pull requests can be made on GitHub if more convenient.