Bump to 0.6.1
Bump to 0.6.1

This release contains fixes to the AddAssign implementation of
Histogram. In particular, we now correctly update all bin counts
and the total count of points on AddAssign.

Signed-off-by: Brian L. Troutwine <ccec23efb0a0e18dff61cc3fd9b4cf2532883527@postmates.com>

postmates/quantiles