Add pre-authorization page to provide additional information

[jonespm]

The new CCM has a nice page prior to the authorization that gives users more information on what is needed. I think having a page like this for this application could be nice.

I think it might also be nice if this page lists what access the application uses and how you could revoke access if you desired.

Ideally Canvas would just give us a way to better customize the authorization page to add our own custom information.