Remove user, role and role_to_users models from StarterPack

[framirez07]

The user, role and role_to_users models definitions are not needed anymore by graphql-server and spa code-generators, now are generated without these model definitions. This models definitions can be removed from StarterPack setup.

Tasks:

• Remove user, role and role_to_user models definitions from StarterPack setup.
• Add some example models definitions to the StarterPack setup (e.g. person, dog, ...).

[framirez07]

Changes completed.
Commits:
f758e88
7e1385d