Provide a better setup experience - enable banner by default and expose permissions

We should provide better experience after the module is installed.

I would like to add the following:
- When the module is first installed, the banner is enabled automatically
- Expose the permission setting on the module configuration page, since it's a common mistake to install the module and miss the configuration on the User permissions page
- Set permissions by default for Anonymous and Authenticated users

This should only affect fresh installs, and those currently using the module should be unaffected by this change.