Adrien Grand cc530b9037 Use t-digest as a dependency.
Our improvements to t-digest have been pushed upstream and t-digest also got
some additional nice improvements around memory usage and speedups of quantile
estimation. So it makes sense to use it as a dependency now.

This also allows to remove the test dependency on Apache Mahout.

Close #6142
2014-05-13 10:38:08 +02:00
..