Update error message when startup fails

Claiming that the loading of maxscale.cnf failed in case of any
error was misleading. Maxscale may not succeed in opening it,
reading it or processing it.

server/core/gateway.c

@@ -1828,10 +1828,11 @@ int main(int argc, char **argv)
 
     if (!config_load(cnf_file_path))
     {
-        char* fprerr = "Failed to load MaxScale configuration "
+        char* fprerr =
+            "Failed to open, read or process the MaxScale configuration "
             "file. Exiting. See the error log for details.";
         print_log_n_stderr(false, !daemon_mode, fprerr, fprerr, 0);
-        MXS_ERROR("Failed to load MaxScale configuration file %s. "
+        MXS_ERROR("Failed to open, read or process the MaxScale configuration file %s. "
                   "Exiting.",
                   cnf_file_path);
         rc = MAXSCALE_BADCONFIG;