Remove MANIFEST.ini

[PennyHow]

Package files are defined in setup.py and MANIFEST.ini. The setup.py file defines individual files nested in modules that are needed in the package distribution, whilst the MANIFEST.ini file defines directories (and all their contents) that should be included in the package distribution.

It would be nicer to have this all defined in the setup.py, rather than in two places, so we can keep better track of all the files that are distributed with pypromice.