Considerations for Application-Specific Security Firewalls

## Considerations for Application-Specific Security Firewalls

### Acceptance Criteria
1. Each firewall in `$app['security.firewalls']` is prefixed with `base.` to prevent the application-specific code from accidentally overwriting the base firewalls.
1. `$app['security.access_rules']` is defined as an empty array so that the application can simply extend it.*

*Otherwise, the application would be burdened with making sure it is defined first, and then extended in every other place. This could be annoying if service providers are moved around, causing errors.