Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=54693.
- Add a validationQueryTimeout property
- Avoid NPE caused by createConnection(..) returns null. (see Comment 6)


git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1521026 13f79535-47bb-0310-9956-ffa450edef68
Preparation for fixing BZ 55534
Add @since markers for common annotations
Fix a few spec non-compliance issues
 - Generated#comment -> commnets
 - DenyAll is permitted on classes

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1521040 13f79535-47bb-0310-9956-ffa450edef68