Revamped the way TileSetBundler mogrifies and writes out bundles

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.

tools/pom.xml

@@ -38,6 +38,13 @@
       <artifactId>playn-core</artifactId>
       <version>1.5.1</version>
     </dependency>
+    <dependency>
+      <groupId>net.sf.json-lib</groupId>
+      <artifactId>json-lib</artifactId>
+      <version>2.4</version>
+      <classifier>jdk15</classifier>
+      <optional>true</optional>
+    </dependency>
     <!-- if you add a dependency here, be sure to hack it into build.xml, yay Ant! -->
 
     <!-- test/build dependencies -->