Create add user function using the pattoo CLI

[DangaRanga]

This should have two user classes with methods from the db.models.py file

• The Modify class which is used for modifying users
• The Add class which is the child of the modify class
  • In the __init__ method will be initialized with the username to be added to the database

[DangaRanga]

This could be done by creating a method by instantiating a method with the username, password, last name and first name (all of the attributes in the user class for the user table)