Low: Build: Support Upstart job config files

How about installing Upstart job (mcp/pacemaker.upstart & pacemaker.combined.upstart) in docdir as an example?
Since installation to /etc/init was dismissed (https://github.com/ClusterLabs/pacemaker/pull/285. umm... although corosync is installed in /etc/init (https://github.com/corosync/corosync/blame/master/corosync.spec.in#L210 ...), I request this.