Fixed API Keys Model & Added Exception

New exception so requirements errors can be handled more nicely if an
implementing client wants.

Updated models to have more control around API keys, list owners, and
set them valid or invalid.
pep8 all the things! (and fix some typo type bugs)

Fixed bugs introduced by making things pep8 compliant and resolved an
issue with API Keys.
pep8 all the things

Okay.... so the whole 79 char thing it doesn't make code more readable,
it makes it less... Is this really strictly abided by?