mitie: New formula

MITIE: MIT Information Extraction provides free (even for commercial
use) state-of-the-art information extraction tools. The current release
includes tools for performing named entity extraction and binary relation
detection as well as tools for training custom extractors and relation
detectors.
`depends_on :python if MacOS.version <= :snow_leopard` and just install the Python file by default (as newer versions ship with Python 2.7)