Make pygments and tornado setuptools packages

These two packages conditionally import setuptools in their setup.py files. If
the import succeeds (like in Python 3.4, where setuptools are part of the
standard library), they become setuptools packages and then later fail to
build, because we need to run our Hashdist specific setuptools options. This
patch fixes it. Essentially, this patch fixes these two packages to build in
Python 3.4.

Fixes #535.