<haproxy_ctld.rb> Bug 962714 - Fix p_usage method to exit immediately

p_usage was run twice when haproxy_ctld was run with -h, since call to
"exit" didn't bypass exit handlers. Changed to "exit!" which drops
straight out of process.

Clone of bug https://bugzilla.redhat.com/show_bug.cgi?id=920990
Merge pull request #2464 from dobbymoodge/BZ962714-haproxy_ctld

Merged by openshift-bot