fix broken link for Report Bugs, point to github

http://scipy.org/BugReport is a broken link. This PR points to the GitHub issues page.

@rgommers said one [would get a medal for this](http://numpy-discussion.10968.n7.nabble.com/Re-Numpy-discussion-was-Raveling-reshape-order-keyword-unnecessarily-confuses-index-and-memory-orderg-tp33522p33569.html) (see G.).

So I think I'll just take this one: :trident: