Adding the change log for the 0.12.3 release.
Adding the change log for the 0.12.3 release.

JPWKU/unix-agent,enStratus/unix-agent,JPWKU/unix-agent,enStratus/unix-agent,enStratus/unix-agent,enStratus/unix-agent,buzztroll/unix-agent,JPWKU/unix-agent,buzztroll/unix-agent,JPWKU/unix-agent,buzztroll/unix-agent,buzztroll/unix-agent