Help with the transition from older pom-scijava versions

Old pom-scijava versions used to define properties such as scifio.groupId
but this is no longer the case. MiniMaven can only handle a single version
of pom-scijava at any given time (to reduce complexity), therefore we run
into problems when there are both dependencies requiring older pom-scijava
versions and dependencies requiring newer pom-scijava versions.

To alleviate the conundrum, let's just fall back to hard-coding those
groupIds for the time until even ImgLib2 has transitioned away from an
old pom-scijava version.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>