Model validation and form rendering amend

Each Validator now defines separate validation rules for the different
controller actions. This is also true for the fields defined on the model.
Update MapperTest to accommodate for changes
Add SQLite configuration to test environment
Added seed data for User model
Modify base TestCase

- Fire Artisan "migration" and "db:seed" commands for each test case.
- Ensure emails are never sent during testing.
Add "updateUniques" method to Validator and associated tests
Define new validation rules on UserValidator
Fix incorrect call to Eloquent constructor
Utilise new functionality exposed by Bozboz\Admin\Services\Validators\Validator
Remove dead code from User