Adds new method for rule merge

IMPORTANT: SecDefaultAction specified on a child configuration will
overwrite the ones specified on the parent; Previously it was
concatenating.

src/operators/detect_xss.cc

@@ -26,7 +26,7 @@ namespace operators {
 
 
 bool DetectXSS::evaluate(Transaction *t, RuleWithActions *rule,
-    const std::string& input, std::shared_ptr<RuleMessage> ruleMessage) {
+    const std::string& input, RuleMessage *ruleMessage) {
     int is_xss;
 
     is_xss = libinjection_xss(input.c_str(), input.length());