Implemented Interfaces are not added to nativization list

Implemented interfaces are not added to the list of assets to nativize when the blueprint class that implements them is flagged for nativization, saved, and compiled. This results in a package failure if packaging is then attempted.

i.e.

[2017.01.25-02.25.37:538][523]UATHelper: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2017.01.25-02.25.37:360][  0]LogBlueprintCodeGen:Error: BP /Game/Blueprints/QA_NativizationCandidate.QA_NativizationCandidate is selected for nativization, but BP interface class /Game/Blueprints/Circular/QABP_Circular_Interface_New_AInter.QABP_Circular_Interface_New_AInter_C is not nativized.

Found on 4.15 Binary CL-3269047

1. Open UE4Editor.exe QAGAME
2. Open Project Settings -> Packaging
   1. Set Blueprint Nativization Method to Exclusive
3. Open QA_TestHelper blueprint asset in blueprint editor
4. Select 'Class Settings' in the blueprints tool bar
5. Implement (via Add button) QABP_Circular_Interface_New_AInter
6. Check 'Nativize' in the class settings.
7. Compile and save
8. Go back to Project Settings > Packaging
9. Expand the 'List of Blueprint assets to nativize'

Result: The implemented interface has not been added to the nativization list