Add Tests for Hive UDF

[prateek]

While doing the work for #9 I missed having some way to get feedback for the hive-udfs, so I spent some time looking around for a way to add tests for Hive. None of the libraries out there are great, the least evil of the lot is Beetest. So I made an example of how that might look.

It's brittle, so I don't think it belongs in the build path. But it might be nice to have for sanity checks in the future. Lemme know if you agree, and I'll add more tests based on that.