Extend pom-scijava

The pom-scijava parent POM not only provides many technical
conveniences, but also signifies that this project is part of the
SciJava software stack.

Since the org.scijava:pom-scijava artifacts are now available in
Maven Central, there is no more issue with this dependency resulting
in any reference to the maven.imagej.net Maven repository.
POM: remove no-longer-needed configuration blocks

The pom-scijava parent declares all the same things,
so there is no need to repeat them downstream.
POM: remove unneeded .git suffixes
POM: fix whitespace and style
POM: depend on the correct ImageJ 1.x GAV

The nih.gov.imagej GAV is obsolete and deprecated. Furthermore, it uses
an incompatible artifact name, resulting in both "ij-" and "imagej-"
artifacts on the classpath of anything that seeks to use Bio-Formats as
a dependency.

Since the net.imagej:ij:* artifacts are now available in Maven Central,
there is no more issue with this dependency resulting in any reference
to the maven.imagej.net Maven repository.