Use Tika's XHTMLContentHandler

While we don't stream anything explictly via sax for now, this is what all parsers included with tika do, and clarifies that Tika's contract is that xhtml should be produced rather than arbitrary xml.
More intrsting demo data, separate schema creation

Schema can now be created by calling DemoSchema.main, DemoIngester still creates the schema as well.
Use a 'users' thema for the demo data, using a names list found on the internets.