MXS-862: Add authenticator options and instances

Authenticators now have a similar mechanism to the `router_options`
parameter which enables configurable authentication.

The authenticators also have a new initialize entry point which is similar
to the createInstance entry point of the filters and routers. The value of
`authenticator_options` is passed as a parameter to this function. The
return vaulue of the `initialize` entry point is passed to the `create`
entry point.

server/modules/routing/binlog/test/testbinlog.c

@@ -105,7 +105,7 @@ int main(int argc, char **argv) {
 			s = strtok_r(NULL, ",", &lasts);
 		}
 
-		server = server_alloc("_none_", "MySQLBackend", (int)3306);
+		server = server_alloc("_none_", "MySQLBackend", 3306, "MySQLBackendAuth", NULL);
 		if (server == NULL) {
 			return 1;
 		}