Set download_url for Pypi
Set download_url for Pypi

Change-Id: I54aa68b5ae348e076e7e4f760c22a78331f29abd

joshhobson/HdrHistogram_py,HdrHistogram/HdrHistogram_py,joshhobson/HdrHistogram_py,HdrHistogram/HdrHistogram_py,lebinh/HdrHistogram_py,lebinh/HdrHistogram_py