rm **kwargs from modules.upstart.full_restart()

* `upstart.full_restart()` already ignores its kwargs
* `daemontools` is the only other service module to implement `full_restart`, and its version doesn't accept arbitrary kwargs
* [According to my research](https://docs.google.com/spreadsheet/ccc?key=0AtlcnvZE4HSKdDMzZGRxWEdVMzBkSVFvRWZwOWM4akE&usp=sharing), no other service module's `restart()` uses its kwargs, and not all of them even accept kwargs in the first place.

So it's neither useful on its own, nor for API conformance/compatibility purposes.