Prepared POMs for Maven Central

The building of the zip assemblies now only happens when the "hudson"
profile is used.
Also, the default Maven repositories are now the Sonatype ones which are
then overriden in the "hudson" profile to the ones of ardor3d.
[maven-release-plugin] prepare release v0.9
[maven-release-plugin] prepare for next development iteration
Merge pull request #55 from neothemachine/sonatype

POM changes for 0.9 release