Add module level static capabilities

The static capabilities declared in getCapabilities allows certain
capabilities to be queried before instances are created. The intended use
of this capability is to remove the need for the `is_internal_service`
function.

server/modules/protocol/MySQL/MySQLBackend/mysql_backend.c

@@ -112,6 +112,7 @@ MXS_MODULE* MXS_CREATE_MODULE()
         MXS_PROTOCOL_VERSION,
         "The MySQL to backend server protocol",
         "V2.0.0",
+        MXS_NO_MODULE_CAPABILITIES,
         &MyObject,
         NULL, /* Process init. */
         NULL, /* Process finish. */

server/modules/protocol/MySQL/MySQLClient/mysql_client.c

@@ -125,6 +125,7 @@ MXS_MODULE* MXS_CREATE_MODULE()
         MXS_PROTOCOL_VERSION,
         "The client to MaxScale MySQL protocol implementation",
         "V1.1.0",
+        MXS_NO_MODULE_CAPABILITIES,
         &MyObject,
         process_init,
         process_finish,