Dropping Python 2

[mahmoud]

Hey folks! Was looking at using hyperlink today and I saw we're a bit behind on supporting the newer Python versions. I started a branch, but ran into trouble getting everything working with Python 2. (The tox even has py26.) The tox.ini is a thing of beauty, one of the most organized I've seen. But how do we feel about dropping Python 2 and getting some new versions in there, @wsanchez / @glyph ?

[glyph]

Let's drop it. I realize we want to be a bit more lenient given that this is a very core-infrastructure sort of thing, but I think 3.6 is the most generous floor by now. 2.x is just silly at this point.