Load a model by name #19

Description

Implement a load model method that will return a model based on the input. Create a second mock model under the same interface. Then create tests for both models using the load model function.

The tests should have a similar structure to the following:

• load a mock model (specificed by some parameter)
• create an empty patch
• call the model's generation function with the empty patch, assert the output to match what you expect the model to do