Drop support for Python 2.4

[cjerdonek]

This is partly because Tox dropped support for Python 2.4 in v1.4.

[bakert]

I have forked this library and dropped python2 support entirely here – https://github.com/PennyDreadfulMTG/pystache

The main reason for doing this is that the current build process no longer works because setuptools has dropped support for the use_2to3 option.