fix: refactored incorrectFeedback and correctFeedback to TrueFeedback…

[livinNector]

… and FalseFeedback respectively

This fixes #62

[fuhrmanator]

@livinNector thanks again for the PR -- I tweaked again the editor to make use of the changes. But I realize this will be a breaking change (API changes) for feedback, which means a major release if I respect NPM's semantic versioning. It's just a number, but I might want to wait for other major changes (other refactorings of the API) before merge/releasing this? What do you think?

[livinNector]

Yeah, I feel that is right. Since I am trying to build the reverse parser (JSON -> GIFT), I feel that some other refactorings could also be considered. I am trying to put together a JSON schema for the parser, will add that soon, this will help us do this refactoring in a cleaner way. And having a JSON schema will be good for documentation purposes also.