Updated my maps: Apollo, Ares, Ares National Park, Poseidon

Removed the oil derrick and mine layer modd in the yaml files, since
they are no longer necessary.
Added new OpenRA map: Artemis

Added new large OpenRA map based on western part of Zeus map. NOTE: The
file on the content.openra website is out of date.
Merge pull request #3396 from wuschel/bleed

wuschel's OpenRA map update