metainfo: Add developer name
metainfo: Add developer name

Looking at the commit history, it appears that while Armin Burgmeier is
no longer an active contributor, he is responsible for the overwhelming
majority of lines of code changed, and his is the sole name in the
README.

According to the Appstream spec
<https://www.freedesktop.org/software/appstream/docs/chap-Metadata.html#tag-developer_name>:

> This tag is translatable.

I have followed this recommendation on the basis that his name might
reasonably be transliterated into non-Latin writing systems.

gobby/gobby,gobby/gobby,gobby/gobby