Changed Helpers#keyname_for to default save for exceptions

I want to start this pull request as a place to start a conversation about the changes that I am starting to make.
It seems like `#keyname_for` is really a version filter. By default it returns the version unless you fit in three different categories (at least at the moment). I changed this to only call out the exceptions but the exceptions aren't really clear to me why they are exceptions or if there are more exceptions in the future.