This is just the output of utils/iana_parse.py and need not be here.

This hasn't (ever?) been used, and it serves little use. There is
similar code in html5lib.constants.
Packaging nowadays is done with distutils.

And hence there is no need for old packaging scripts.
Update README, and move to using reST. Fixes #5, #22.
Ensure README and requirements files are included in sdist.