Don't match > as closing tag within HTML attributes

[treyhunner]

Previously running smartpants against <div data-condition="a > b">text</div> would have resulted in the second " being converted to a smart quote like <div data-condition="a > b&#8221;>text</div>

This fixes that issue and adds a test.

I noticed that the Makefile and setup.py setup are quite outdated. In case you have trouble testing, note that I had to run pip install docutils pygments to run python setup.py test successfully.