Fix. Migration didn't work when adding the foreign key 'role_id' in the users table. The column 'role_id' should be added as an unsigned integer in the user table.
Added validation to the data passed via the promp
Adding a seed, that way when the user installs the package and runs the db:seed command, gets some defauls roles, permissions and an Admin user. Also updated the README file with the new instructions.
Merge pull request #7 from gpopoteur/develop

Added role_id UNSIGNED to the user migration, Validation to the data passed through the prompt and a Seeder for the DB