Event hook fix

[dajt1725]

Make device_changed and job_failed event_hook calls work.

[coldfix]

Hi,
I wouldn't consider this a fix, but rather a new feature.
Introducing a fake device property to provide job properties doesn't really make sense. A job is not part of the device, it is what changes a device.
Just curious, what you're trying to achieve, and if it might be better for you to implement your own udisks client instead of getting too involved on the level of installing hooks from udiskie, see https://github.com/coldfix/udiskie/wiki/Python-API for a minimal example.