Using json in stead of yaml

The yaml seem to be causing a lot of issues, and is failing "all the time", or at least very often.

I had a look at the tika documentation (here: http://tika.apache.org/1.5/gettingstarted.html)

It supports outputting of json, which would apparently have better performance (https://gist.github.com/aishfenton/480059).

I made an implementation of yomu using JSON in stead of yaml. This way the lib would not cause so many errors, and possibly be a lot faster :)

I have updated tests to accommodate this change. There are a few new methods as well. I added a "creation_date" method because the JSON does not automatically parse the time.

I also bumped the version number, which might be "your job". I suspect this actually qualifies as a bump in the 0.X version because of the new features.

Anyway, love the library, so I hope this fixes some of the issues I was having with it :)