Missing MIT license terms

According to the [setup.py](https://github.com/bukzor/python-coverage-enable-subprocess/blob/master/setup.py#L129) file this software is released under terms of [MIT](https://spdx.org/licenses/MIT.html) license.  The MIT license requires that the license text should be included in the software.  Please add full MIT license terms to this software.  Thank you.