Add an option to the Context to control the blocking of XML external entities when parsing XML configuration files and enable this blocking by default when a security manager is used. The block is implemented via a custom resolver to enable the logging of any blocked entities.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1549529 13f79535-47bb-0310-9956-ffa450edef68
Fix Javadoc

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1549534 13f79535-47bb-0310-9956-ffa450edef68
Fix Javadoc warning

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1549535 13f79535-47bb-0310-9956-ffa450edef68