ElementalAreaController should not be a subclass of CMSMain

[GuySartorelli]

Right now ElementalAreaController is a subclass of CMSMain.
There's almost certainly no good reason for this as-is, but with the refactoring of LeftAndMain, CMSMain, etc it's even less sensible.

Acceptance Criteria

• ElementalAreaController is a subclass of the class that's most appropriate which provides permissions and routing for a admin/* route along with form schema functionality.