sort_index was deprecated in pandas 0.17. Make its use conditional.
sort_index was deprecated in pandas 0.17. Make its use conditional.

This patch gets rid of the "deprecated" warning when using Pandas
versions older than 0.17 (vs the last patch), but also makes pyjstat
compatible with versions of Pandas < 0.17 (vs the current master head).

robottwo/pyjstat