Use dataTypeClass to help support type safety in scala

[smrutimo]

No description provided.

[mcallisto]

@smrutimo do you think your PR would solve the following:

I can load a case class Foo definition with
dataType = "models.Foo"

But it doesn't work with
dataType = "forms.Bar.Foo" // compile error java.lang.ClassNotFoundException
where Foo is contained in object Bar

I can reach the class with
dataTypeClass = classOf[forms.Bar.Foo]
but it has no visible effect, the type is not displayed.