Fix iopubwatcher.py example script.

Should I PEP8 this?

```
examples/parallel/iopubwatcher.py:1:80: E501 line too long (91 > 79 characters)
examples/parallel/iopubwatcher.py:3:80: E501 line too long (95 > 79 characters)
examples/parallel/iopubwatcher.py:5:80: E501 line too long (92 > 79 characters)
examples/parallel/iopubwatcher.py:6:80: E501 line too long (89 > 79 characters)
examples/parallel/iopubwatcher.py:9:80: E501 line too long (93 > 79 characters)
examples/parallel/iopubwatcher.py:25:1: E302 expected 2 blank lines, found 1
examples/parallel/iopubwatcher.py:35:24: E228 missing whitespace around modulo operator
examples/parallel/iopubwatcher.py:42:80: E501 line too long (85 > 79 characters)
examples/parallel/iopubwatcher.py:53:19: E231 missing whitespace after ','
```

Did I make this script less general by removing the `disambiguate_url` stuff? I'm not sure. 

This fixes [issue #5057](https://github.com/ipython/ipython/issues/5057).