Add matchers for model actions.

[thomasfedb]

Add matchers for model operations, syntax as follows:

• expect{subject}.to create(Model)
• expect{subject}.to create(Model).with(params)
• expect{subject}.to update(Model)
• expect{subject}.to update(instance)
• expect{subject}.to update(instance).with(params)
• expect{subject}.to delete(Model)
• expect{subject}.to delete(instance)

[thomasfedb]

Version 1.3.0 implements expect{subject}.to create(Model).

[thomasfedb]

Version 1.3.3 implements expect{subject}.to update(Model).