Internal Compat

Adds compatibility tests to ensure that parquet files can be read and written between Hive and MR.
Do you have any objection to using a style like:
```
class MRWriteJob(location: Option[String], db: String, dst: String, args: Args) 
  extends Job(Args(args.m ++ Seq("db" -> db, "dst" -> dst) ++ location.map("location" -> _)))
```