SgEntity.revert() does not mark return as True if invalidate() returns False

The revert() call now looks at the return value of invalidate() and if its False
the field does not contribute to the return of revert() being True.  This was
causing an issue with "id" and "type" fields causing revert() to always return
True.
Removed debug print statement left in previous commit
Merge branch 'develop'