`Embeddable::Xhtml.model_name.human` -> `"Xhtml"` the human method strips out the module for you.
The way a name is modified from the default class name is by using config/locals. There is an example there already so that Portal::Clazz shows up as Class in rails validation messages which use `Class.model_name.human`

    en:
      activerecord:
        models:
          "portal/clazz": Class

So if we wanted to localize to another language we'd use the same key. just under a different language code.

Going forward I think we should use `Class.display_name` not `t(Class)`. `t(Class)` would require a key for the class name itself, and it would mean that built in Rails validation messages would not get the correct name.