Added code to check that objects have @Column annotations

If a class to be encoded has no @Column annotations the CodecGen
should throw an Exception, as a class with no @Column annotations
cannot be correctly represented on protobuf. I added a check to
scanFields to check for this, and throw an appropriate exception.

Change-Id: Ib6962d1b2e05e5b494ca0cee2091caa1f5daa731
1 file changed