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.

Further, pom-scijava includes many more desirable configuration blocks,
as well as workarounds for various bugs, etc. By extending pom-scijava,
Bio-Formats automatically inherits this helpful configuration, so that
it can avoid painfully encountering all the same issues which have
already been solved in other SciJava projects.
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The nih.gov.imagej GAV is obsolete and deprecated.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.