Soft Model Retrieval Methods

[aaemnnosttv]

As it is, the current methods for retrieving a model instance are all "hard" methods, in that they all throw a not found exception in the event that there is no record found for the given ID, slug, etc.

There are times however when an exception is not necessary and a simple falsy value would be more efficient. This would allow for more flexibility by not forcing the user to handle exceptions in all cases.