Add switch between STAGING and RELEASE repositories

The Sonatype STAGING and RELEASE repositories are now auto-selected
depending on whether the version number has a STAGING or RELEASE suffix.
Remove unused bzip2 library

Osmosis used to depend on an Apache bzip2 library that was not available
on Maven Central (part of Ant I think ...).  This has been replaced by
the commons-compress library so the old library can now be deleted from
the Osmosis repository.
Add osmosis-osm-binary project

This is a custom version of Scott Crosby's OSM Binary project to avoid
depending on a pre-compiled jar.  This is necessary for publishing to
Maven Central.  See the readme.txt in the project for more details.
Update PBF project to use internal OSM Binary project

The PBF project was depending on a pre-compiled jar included in the build-
support ivy project.  This change switches it over to use the osmosis-
osm-binary project which is an Osmosis customised version of the
original library.
Remove the osmpbf pre-compiled jar

We no longer require the pre-compiled osmpbf.jar because it is
superceded by the osmosis-osm-binary project.
Remove internal Ivy repository

All dependencies are now available on Maven Central, therefore we don't
need to maintain an internal Ivy repository any longer.