options.autocompleteOptions undefined throw error

Hi,

First thanks for the wonderful plugin. I notice a bug when there is no autocompleteUrl being given during initialization. 

I suggest changing line 256 of jquery.tagedit.js

from 

```
if(options.autocompleteOptions.source != false) {
```

to 

```
if(!!options.autocompleteOptions.source) {
```

Once again, thanks for the good work 

Cheers,
