Add syslogging capabilities to nova-rootwrap, if you set parameter
use_syslog to True. You can specify a facility (syslog_log_facility)
and level (syslog_log_level) to use. Finalizes bp nova-rootwrap-options.
In doing so, it moves rootwrap config parsing to a nova.rootwrap.wrapper
object (and adds unit testing for it). It also improves log messages
content (including the name of the matching filter and the escalation
path used). Incidentally fixes bug 1084766.
Change-Id: Idb8cd9c9febd6263dafab4bc2bff817f00c53dc0
8ec48fff8f