Adds AuditLog class

The properties related to the Audit Log were saved into the classes
Rules and Dirver, now all those properties will be saved into the
AuditLog class.

headers/modsecurity/rules.h

@@ -39,6 +39,7 @@ class Driver;
 
 namespace ModSecurity {
 class Rule;
+class AuditLog;
 
 /** @ingroup ModSecurity_CPP_API */
 class Rules {
@@ -85,6 +86,8 @@ class Rules {
     DebugLog *debug_log;
     void debug(int level, std::string message);
 
+    AuditLog *audit_log;
+
  private:
     int m_referenceCount;
     DebugLog *m_custom_debug_log;