Move service user injection into MySQL authenticator

The MySQL authenticator now injects the service user into the list of
allowed users if loading of database users fails. This allows the removal
of common code in the binlogrouter and maxinfo modules.

include/maxscale/router.h

@@ -100,9 +100,7 @@ typedef enum router_capability_t
     RCAP_TYPE_UNDEFINED     = 0x00,
     RCAP_TYPE_STMT_INPUT    = 0x01, /**< Statement per buffer */
     RCAP_TYPE_PACKET_INPUT  = 0x02, /**< Data as it was read from DCB */
-    RCAP_TYPE_NO_RSESSION   = 0x04, /**< Router does not use router sessions */
-    RCAP_TYPE_NO_USERS_INIT = 0x08  /**< Prevent the loading of authenticator
-                                       users when the service is started */
+    RCAP_TYPE_NO_RSESSION   = 0x04 /**< Router does not use router sessions */
 } router_capability_t;
 
 MXS_END_DECLS