Didn't like previous change.

setuptools only looks for txt and rst (or extensionless) README files.
Added .md extension to its READMES constant variable before calling
setup().

To keep version/author/license info in the main module, I couldn't
import since setup() has to be called before figuring out dependencies,
and to avoid having a one-file package version.py couldn't be part of
py_modules. Solution is to use ast.literal_eval.