Generated admin_user file should be plural

[rmw]

This is both consistent with the modal generator and prevents load errors.

I was writing a gem and testing against active_admin and got load errors on the admin_user path.

[seanlinsley]

The standard seems to have changed so that all app/admin files are singular, hence why the Dashboard and AdminUser files are singular if you create a new project.

[seanlinsley]

I personally prefer the singular form. It's more consistent with Rails naming conventions.

[rmw]

I got load errors with the singular in a rails app although it was a test app inside a gem, which could have some strange behavior (using rails plugin new --full). The errors were fixed by making the files plural.

But I understand where you're coming from. Our app started with an older version of ActiveAdmin and our models are plural, so I thought that was the standard.