FORGE-1888 Restrict REST resource generation to simple JPA entities.

JPA entities with composite keys will be excluded from REST resource
generation. They will not be displayed in the dialog for generation.
FORGE-1914 Corrected REST resource generation logic for primitives

Primary keys of primitive types are now handled correctly.
They're boxed back to objects before the equals method is invoked.
Removed unnecessary check for key of JPA entities.
Merge pull request #479 from VineetReynolds/FORGE-1888

FORGE-1888 and FORGE-1914