MXS-1929: Take serialization helpers into use in service

The service configuration serialization now uses the helper functions from
config.hh. This fixes the failing test mxs1731_old_persisted_config and
improves the readability of persisted configuration files.

Converted parameters into booleans that were used like booleans. This
forced the removal of the automatic enabling of
localhost_match_wildcard_host but since it has been enable by default,
this change should have no practical effects.

In addition to the clarification of the persisted configurations, this
change will limit the negative side-effects of changing a configuration
value in the main configuration file after a runtime modification has been
made. If a value has not been modified at runtime, changes to it in the
main configuration will take effect.

Previously, a runtime modification prevented all further manual changes to
the configuration file. Although in theory this sounds good, in practice
this does very little to improve the situation: The only reliable way to
change a parameter after a runtime modification is to do it via the REST
API (or MaxAdmin).

include/maxscale/service.h

@@ -114,8 +114,8 @@ typedef struct service
     char user[MAX_SERVICE_USER_LEN];   /**< The user name to use to extract information */
     char password[MAX_SERVICE_PASSWORD_LEN]; /**< The authentication data requied */
     SERVICE_STATS stats;               /**< The service statistics */
-    int enable_root;                   /**< Allow root user  access */
-    int localhost_match_wildcard_host; /**< Match localhost against wildcard */
+    bool enable_root;                   /**< Allow root user  access */
+    bool localhost_match_wildcard_host; /**< Match localhost against wildcard */
     MXS_CONFIG_PARAMETER* svc_config_param;/**<  list of config params and values */
     int svc_config_version;            /**<  Version number of configuration */
     bool svc_do_shutdown;              /**< tells the service to exit loops etc. */