Consider `zfcadmin` for `ZfcAdmin\Controller\AdminController`

[claytondaley]

When using ZfcRbac, I was able to guard the controllers zfcuser and zfcuseradmin, but when I wanted to guard zfcadmin (which doesn't exist), I had to dig up ZfcAdmin\Controller\AdminController. Not complicated, but it'd be nice to provide a uniform naming scheme across Zfc* modules.

[stijnhau]

That might be true.
Just create a PR for it.