Affability

- Understand function now reraises the InvalidArgument exception thrown by DialogFlow. This allows for better error handling when using the understand function, and is demonstrated in the sample usage file.
- Fixes understand function returning reply instead of reply parameters for replyParams. replyParams of the returned organizer class now contains the correct reply parameters
- Removes sample usage file from the package build

- Adding thorough comments for readability
- Changing Affability to affability (lowercase) for pragmatic purposes (such as ease of typing)
- Automatically installing DialogFlow when installing Affability (as it is a critical dependency)