Issue 04-Add role entity to the model

[ScotterMonk]

Completed

See https://github.com/ScotterMonk/scottswain/pull/6 for details.

Assignment

Allow for the creation of one or more roles with attributes:

• role_id
• role_name
• department_name. Combination of role_name and department_name is unique. Allow for a user to be assigned one or more roles and for a role to be assigned to one or more users. Users_roles table relies on roles_lookup for putting a name and dept to a role id.

[ScotterMonk]

PR: https://github.com/ScotterMonk/scottswain/pull/6