www-apps/otrs: Designate new maintainer in metadata, bump to -4.0.12

www-apps/otrs: Designate new maintainer in metadata, bump to -4.0.12

New maintainer added & supported under the proxy-maintainers herd, testing
and revision carried out thanks also to wraeth, fix to broken .png file
applied according to past bug #466190 supplied by Blackb|rd, all patches and
revisons of ebuilds supplied via bug cited below, releases after -3.2.12
skipped, holding off from beta versions of version 5.x for now, removed old
versions prior to -3.2.12. Finally closes the gentoo bug.

Gentoo-Bug: 506052

Package-Manager: portage-2.2.20.1