Field Overrides: Work in Progess

We just wanted to start a place for discussion of this feature as it evolves.  

Primarily for @cpennington @carsongee @pdpinch @davisagli 
Because CWSM is overloaded enough already. It's got both Scope.student_state and grades in it. Also, by storing your POC overrides in the same json blob that the Scope.student_state is in, there might be unexpected consequences with the existing field storage. Finally, storing the field data in json blobs in SQL was a mistake that I don't really want to repeat.