Adding a test case for calling tangelo.accessor with a function

Currently this test fails with:
```
Error: [tangelo.accessor()] I am an undefined accessor - you shouldn't be calling me!
    at Object.tangelo.fatalError (http://localhost/~jbeezley/cluster/js/tangelo.js:36:15)
    at func (http://localhost/~jbeezley/cluster/js/tangelo.js:223:25)
    at null.<anonymous> (http://localhost/~jbeezley/cluster/accessorFunction.js:14:16)
```