LOGBACK-960 Prevent a possible NPE in SyslogAppenderBase.close() when the SyslogOutputStream is null (due to a host lookup failure for example)
LOGBACK-960 Update release notes
Update release notes: swap NPE with NullPointerException for consistency and fix a couple typos
Merge pull request #179 from ericdahl/logback-960

LOGBACK-960 Prevent a possible NPE in SyslogAppenderBase.close()