MINOR: httpclient/cli: access should be only done from expert mode

Only enable the usage of the CLI HTTP client in expert mode.
diff --git a/src/http_client.c b/src/http_client.c
index cfbff19..f298fe1 100644
--- a/src/http_client.c
+++ b/src/http_client.c
@@ -236,7 +236,7 @@
 
 /* register cli keywords */
 static struct cli_kw_list cli_kws = {{ },{
-	{ { "httpclient", NULL }, "httpclient <method> <URI>   : launch an HTTP request", hc_cli_parse, hc_cli_io_handler, hc_cli_release},
+	{ { "httpclient", NULL }, "httpclient <method> <URI>   : launch an HTTP request", hc_cli_parse, hc_cli_io_handler, hc_cli_release,  NULL, ACCESS_EXPERT},
 	{ { NULL }, NULL, NULL, NULL }
 }};