To honor RFC5424 add use_syslog_rfc_format config option

Since the rootwrap code was graduated to a separate library,
This change completes one from oslo-incubator:
Backport 'ident' from python 3.3 for Oslo's SysLogHandler
(with commit 79e8a9a08daf563aa8a8d9280c9a6a27dcafc8f2)

To honor RFC5424 add use_syslog_rfc_format config option
(default False, would be deprecated in J after existing
syslog format deprecation) which adds APP-NAME to syslog message
before MSG part to reflect application or service name.
Usable only with use_syslog, otherwise ignored.

During J, the default logging format for syslog should be changed
to always provide APP-NAME, thus use_syslog_rfc_format could be
deprecated in J as well.

Closes-bug: #904307

Change-Id: Icff9db07d543738e092a8826e8a0d2e4b213fc38
Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>
Merge "To honor RFC5424 add use_syslog_rfc_format config option"