destroy unit tests not valid

destroy unit tests not valid

I just noticed that .resizable('destroy') has been broken for a long time, possibly always.  The destroy method throws an error and the resizable isn't destroyed.  The unit tests all pass though, so I'm guessing that all of our plugins have invalid destroy tests.
I've got a fix for resizable that I'm getting ready to commit, but we should figure out some better tests.  Also, I'm not sure why any code that throws an error doesn't cause the test to fail.