ascli: Add vercmp shorthand for compare-versions subcommand

tools/appstream-cli.c

@@ -994,7 +994,7 @@ as_client_run (char **argv, int argc)
 		return as_client_run_status (argv, argc);
 	} else if (g_strcmp0 (command, "convert") == 0) {
 		return as_client_run_convert (argv, argc);
-	} else if (g_strcmp0 (command, "compare-versions") == 0) {
+	} else if ((g_strcmp0 (command, "compare-versions") == 0) || (g_strcmp0 (command, "vercmp") == 0)) {
 		return as_client_run_compare_versions (argv, argc);
 	} else if (g_strcmp0 (command, "new-template") == 0) {
 		return as_client_run_new_template (argv, argc);