Add autosystemname setting to asterisk.conf

When enabled, it will set the systemname to be the hostname of the system

Issue 9713, patch by Juggie - slightly modified by me, to "failover" to localhost


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@63967 65c4cc65-6c06-0410-ace0-fbb531ad65f3