pull sasl config out of registration

myirc/include/registration.hpp

@@ -2,12 +2,10 @@
 
 #include "connection.hpp"
 #include "client.hpp"
-#include "ref.hpp"
 
 #include <memory>
 #include <string>
 #include <unordered_map>
-#include <unordered_set>
 
 class Registration : public std::enable_shared_from_this<Registration>
 {
@@ -17,11 +15,7 @@ public:
         std::string username;
         std::string realname;
         std::string password;
-        std::string sasl_mechanism;
-        std::string sasl_authcid;
-        std::string sasl_authzid;
-        std::string sasl_password;
-        Ref<EVP_PKEY> sasl_key;
+        std::unique_ptr<SaslMechanism> sasl_mechanism;
     };
 
 private: