Fix bug with nil update_attributes

update_attributes(nil) typically returns true (nothing to update, has to succeed). With attr_encrypted installed it throws, so a simple test substitutes an empty hash.

This occurs in spec tests more than in nature

I tested with both versions of ActiveRecord. A simple clean fix.  Thanks

I see now this is a dupe of #87, but my fix seems cleaner (though slower)

BTW tests failed before and after changes with .stubs missing from user