Create explicit MSave, MFindById, etc. instead of using variadic paramaters for greater flexibility. Can now perform finds on models with different types in a single transaction. Discovered error in util.compareAsStringSet, so TestModelWithSet is currently commented out.
Fix bug in util.compareAsStringSet. Add a test so it wont happen again.
uncomment TestModelWithSet. Since the bug in util.compareAsStringSet was fixed, it passes now.