new formula: MADlib 1.6.0.

MADlib: Big Data Machine Learning in SQL for Data Scientists.

MADlib is a library that allows you to apply many statistical
and machine learning algorithms to data that resides in a DBMS
(PostgreSQL).

This formula has been tested with OS X Lion (10.7.5) and OS X Mavericks (10.9.4).
This can't be changed to `bin.rmdir` because `bin` is a symbolic link.