Allow users to specify a list/map of ContentHandlerFactories in tika-config.xml

I'd like to add a tika-eval handler that will calculate text stats at the end of parsing a document so that the user can get a unified/simpler view of number of tokens/ out of vocabulary, etc. in the metadata rather than having to run their own post-parse process on the content.

The problem comes with integrating this into tika-app and tika-server – tika-app balloons to 134MB. I don't want to nearly double the size of tika-app just so that I can add some stuff that very few folks will use.

I think we've discussed this option before, but it would be handy to allow users to specify a ContentHandlerFactory or possibly a map of ContentHandlerFactories in tika-config.xml so that users can get custom handling in tika-app and tika-server.

The idea of a map of ContentHandlerFactories, would be to have a name for each content handler factory, and a user could call different handlers on tika-server like this:

curl... http://localhost:9998/tika/custom/myhandler1
curl... http://localhost:9998/tika/custom/myhandler2

That's not right because we'd want to differentiate classic Tika parsing and the RecursiveParserWrapper...

curl... http://localhost:9998/tika/myhandler1
curl... http://localhost:9998/tika/myhandler2

curl... http://localhost:9998/rmeta/myhandler1
curl... http://localhost:9998/rmeta/myhandler2

or in tika-app:

java -jar tika-app.jar --handlerFactory=myhandler1...

WDYT?