WidgetDemo: update StatusService package to latest
Use latest version of pom-scijava

Among other things, this version specifies a release version (rather
than a SNAPSHOT) for the scijava-common dependency.

This may not matter directly for these tutorials, since for simplicity,
they inherit the scijava-common dependency transitively, despite making
use of org.scijava classes directly.

However, I think it is still better to use the newest available
pom-scijava, so that when people copy and paste these POMs (which is
expected since they are tutorial code), they start from the newest
available version.
Use imagej.net domain name for ImageJ list URLs

This is slightly more convenient and future-proof than the
imagej.nih.gov/ij prefix.