Fix PyPI error

"Checking dist/linkpred-0.6-py3-none-any.whl: FAILED
ERROR    `long_description` has syntax errors in markup and would not be
         rendered on PyPI.
         line 14: Warning: Explicit markup ends without a blank line; unexpected
         unindent.
Checking dist/linkpred-0.6.tar.gz: FAILED
ERROR    `long_description` has syntax errors in markup and would not be
         rendered on PyPI.
         line 14: Warning: Explicit markup ends without a blank line; unexpected
         unindent."

Version 0.5.1

I hit this bug in Travis that prevents me from using token
authentication and can't get the workaround to, er, work
(travis-ci/travis.rb#687 (comment)).
Hence, version 0.5 is botched and we have v0.5.1...

v0.4.1 - Python 3.7 compatible!

linkpred v0.4

Allow specifying Precision-at-k

Fix test that sometimes failed because of hash randomization