Use ClassLoader.getSystemResourceAsStream() instead of <classname>.class

Commit message: Use ClassLoader.getSystemResourceAsStream() instead of <classname>.class... getClassLoader() to avoid catching an Error-throwable, which shouldn't have been done in the first place. Avoids suspending the debugger because of ClassNotFoundException raised (at least in Eclipse's debugger) by it.

I shouldn't have done that in the first place, so sorry about that. This seems to work much better, though the downside is that when one is using a separate ClassLoader than with the one the application is launched, the properties cannot be loaded. In that case the version will still be set to unknown, and I think that's not a common usecase. This also cleans the code a bit :-)