Introduced a Writer class to hold all the options to the createBundle method and help clarify
things. This also ended up being a convenient place to put the previous member variables since
they affect the process in pretty much the same way.
Got rid of DirectoryTileSetBundler. This had a mutated copy of a method from TileSetBundler,
that appeared to be missing some bug fixes. Anyway, it shouldn't be needed anymore, callers
can use a BundleWriter that is a directory.
Added an option for outputting tileset bundle metadata as json. This includes some
utility classes and the net.sf.json-lib dependency. This follows the same pattern
as some other tools only jars so should end up being ignored by production
applications.
Michael Bayne