fix problems using juice with node 9.3

1. bumped version of jsdom to 0.2.19 to use node-gyp instead node-waf for contextify packaged on which jsdom depends on.

2. fix problems with test/cases/* for new version of jsdom. jsdom wraps snippets of html into *html.body* tags to form correct html document which will be accessible via document.innerHTML property. But all test/cases/*.(html | out) cases documents was only snippets, not valid html documents - so tests fails becouse of jsdom wrapping.

4. add new test/cases/empty* set of test documents to ensure that *juice* is shy and tidy and don't touch anything he shouldn't ;-)

5. bumped version to 0.0.7