Fix scope class name when setting resource by token

[mcelicalderon]

Hi! I'm pushing this change without tests just to make sure the change makes sense before actually writing the specs.

I noticed the scope name is no properly set for models that exist within another model like Users::Customer. I see in places like this that you actually handle that so not doing the same in the concern was probably just overlooked.

The current scope = rc.to_s.underscore.to_sym will generate users/customer as the scope name and this is a problem as the devise mapping name will be users_customer. The problem with this and the reason I saw this is that when using the sign_in method, warden will try to serialize the resource and when trying to do so here and here it will fail to find the custom devise serializer for the model and will simply use serialize. This can (and has happened to me) lead to cookie overflows as the model can be potentially big default serialization will include all columns in the serialized string.

Let me know what you think, happy to add specs if you think this is fine, but I guess I would have to add another model scoped to a module in order to do so.

[MaicolBen]

It makes sense, so yeah add specs

[mcelicalderon]

Sure, will do as soon as possible.