[468959] Support an extensible product catalog
[468959] Support an extensible product catalog

https://bugs.eclipse.org/bugs/show_bug.cgi?id=468959
peterkir/org.eclipse.oomph,peterkir/org.eclipse.oomph,peterkir/org.eclipse.oomph,peterkir/org.eclipse.oomph,peterkir/org.eclipse.oomph