Create EMDUnifrac python package

[abremges]

I'd like to list EMDUnifrac as an external dependency for our joint project. The easiest way would be if you package and distribute EMDUnifrac, users could then install it, e.g. via pip.

For now, I simply copied the EMDUnifrac.py source file into my project – which is easy enough, but harder to keep track of (and might eventually clash with your GPL licensing).