Ebuild cleanups / Nothing special

Hi, some cleanups, nothing special.

FYI, the mate team is now preparing for a 1.6 release. I see git commits bumping versions to 1.6. I would like to see more testing of the release and the ebuilds soon :-)

Greets
~infirit

edit: messed up on the fyi, s/versions to 1.5/versions to 1.6/