OF-560: drop support for Pack200 compression

For distribution of Openfire some of the shipped jar files have been compressed with Pack200.
This PR drops the compression in the build system for distribution- and plugin-builds.
It drops also the unpacking on the server start.

See https://igniterealtime.org/issues/browse/OF-560 for further information

I've tested the distribution build itself. It's starts without any issues.
Test's that we should do before we merge the PR into the master:
* Test the debian package
* Test Install4J-Package for Windows.