Refactor Pharrell global object to use Environment instance :neckbeard:

This means that the configuration state is all held within an instance
that is held in one static reference rather than having multiple static
variables hanging around. Might allow for a cleaner internal interface and
a more modular setup.
Remove coveralls
Don't need to ignore that no more
Moar spelling mistakes :blush:
Make error messages more descriptive
Improve README wordings