Requirements differ from instructions in readme

[pasjohnj]

I got the parser working. In addition to :

• Python 3.4+
• amara3-xml package
• html5lib package
• pytest (for running the test suite)

I also needed to install the package rdflib, and the version of the amara3-xml package found [here](https://pypi.python.org/pypi/amara3-xml/3.0.0a6?
pip install “amara3-iri>=3.0.0a2”).

Installing amara3-xml as in the instruction threw an error at this point:

from amara3 import iri

Installing the other version got the tool working without issue.