Experiment with new `ethash` library

[pipermerriam]

What is wrong?

There is a new set of bindings released for ethash

https://github.com/chfast/ethash/tree/v0.5.1-alpha.1/bindings/python/ethash

They might also include progpow?

How can it be fixed

We need to try them out.

[matnad]

This would likely also fix the issues caused by the current (unmaintained) pyethash library. See discussion in https://github.com/ethereum/ethash/pull/107 (pyethash and as an extension your project currently can't be installed via pip on anything but linux without manually modifying the pyethash files)