Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=56383
Use non-empty title when both showServerInfo and showReport are false.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1590438 13f79535-47bb-0310-9956-ffa450edef68
Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=56383
Document the new feature on the "security HowTO" page.
Move error valve documentation lower in the valves list
(access log valves and access control valves should be the first ones there).

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1590451 13f79535-47bb-0310-9956-ffa450edef68