Replaced bare except with except Exception

This was required to get [gevent.Timeout](http://www.gevent.org/gevent.html#timeouts)'s working:

```
with gevent.Timeout(10):
    goose.extract('http://example.com')
```

Without that, Timeout instance raised by gevent was catched by bare except, and there was no way to abort this code execution.

It is a bad practice to use bare except, since there are some exceptions like GeneratorExit, KeyboardInterrupt, SystemExit which are not errors, but still could be thrown in any part of the code, and usually you should not catch them.