BLD: numpy 1.16.1 failing builds
looks like our builds are failing as we are now picking up numpy 1.16.1; I belive 1.16.2 fixes this, so once this is fully pushed should be ok.

These failures manifest with pytables. https://travis-ci.org/pandas-dev/pandas/jobs/500453356

cc @pandas-dev/pandas-core 

let's hold off merging for now / we could simply pin numpy=1.15.* as well (again for now), if someone wants to do this.