Net::Duo To-Do List

APIs:

 * Add support for modifying groups, integrations, and tokens via the
   Admin API.

 * Add calls for the administrators, settings, and account info portions
   of the Admin API.

 * Flesh out the rest of the Auth API, particularly including support for
   preauthentication.

 * Add support for the Verify API.

 * Add support for the Accounts API.

Test suite:

 * Test::RRA::Duo should dynamically discover the fields that can compared
   with simple comparisons, and the fields that can be compared with
   is_deeply, by analyzing the return of _fields in the relevant class.

 * Add additional tests for all the error handling cases and then check
   test coverage.