DOC Link to github Quantopian logo rather than locally.

Author: twiecki

README.rst

@@ -145,6 +145,6 @@ Sponsors
    :target: https://coveralls.io/github/pymc-devs/pymc3?branch=master 
 .. |NumFOCUS| image:: http://www.numfocus.org/uploads/6/0/6/9/60696727/1457562110.png
    :target: http://www.numfocus.org/
-.. |Quantopian| image:: docs/quantopianlogo.jpg
+.. |Quantopian| image:: https://github.com/raw/pymc-devs/pymc3/master/docs/quantopianlogo.jpg
    :target: https://quantopian.com