[WIP][SPARK-2097][SQL] UDF Support

Remaining:
 - [x] Python Support
 - [x] Python Test cases
 - [x] Move out of hive
 - [ ] scala Test cases
 - [ ] Input coercion?
The value was in the second column in the original relation.  However, `select('value)` is projecting only the value column into the first column.