Full module name for Legato::Model

This fixes a problem that wasn't present until recently, possibly due to an update to the Legato gem.  `Sufia::Analytics.profile` takes as a method a custom defined class such as `Sufia::Download` or `Sufia::Pageview`.  Previously, you only needed to pass either `download` or `pageview`, but that has changed and now you must use `sufia__download` which is then converted to `Sufia::Download` by `Legato::ProfileMethods.method_name_from_klass`.