exceptions raised when running on non-standard ports like 8000

When using raven-js on a site running on a non port 80/443 server, doing this fails:

``` javascript
// capture an exception
try {
 errorThrowingCode();
} catch(err) {
 Raven.captureException(err);
}
```

i.e. running locally for testing on http://localhost:8000 (with that set as allowed origin for CORRS), you'll get raven exceptions as it strips the from the ":" on wards.
