Add sro gem
Add shoulda-matchers gem
Set migration for active_record_models to create temporary table
Refactor validation test in sign_up model to check for uuid, not email
(red) Write failing test => SignUp should require email to be set
(green) Make test pass => SignUp should require email to be set
(green) Write passing test => SignUp should require case sensitive
unique value for uuid

- Had already added the code in a previous commit
(red)  Write failing test => SignUp#uuid should be a valid UUID
(green) Make test pass => SignUp#set_uuid should be a valid UUID
Refactor model tests for SignUp
(green) Write passing test => SignUp#set_uuid does not alter existing
Uuid
Refactor model tests for SignUp
(red) Write failing test => SignUp#to_param returns a valid UUID
(green) Make test pass => SignUp#to_param returns a valid UUID
Refactor model tests for SignUp
Refactor SignUp model