logging: role; local UDP based; with forwarding

Python <2.7.4 has an issue with direct unix socket syslog logging.
During a rsyslog service restart, the socket is closed and re-opened but
the services using the logging improperly handle the socket close and
start to fail. These services consume 100% of CPU resources until they
are restarted.

This change works around the problem by using rsyslog to listen on
514/udp and the imfile module to follow some individual OpenStack
service logfiles and forward them onto the central logging server.

All nova, cinder, keystone services log to the local UDP port by
default. Only some services need to be manually followed which is
defined in the defaults for the logging role.

Relevant links:
 - https://bugs.launchpad.net/mos/+bug/1363102
 - http://bugs.python.org/issue15179