Auth basic: "info" logging level on no user/password.

This isn't an exceptional condition and normally happens on
first request from a client.
diff --git a/src/http/modules/ngx_http_auth_basic_module.c b/src/http/modules/ngx_http_auth_basic_module.c
index e8709e5..8ec5329 100644
--- a/src/http/modules/ngx_http_auth_basic_module.c
+++ b/src/http/modules/ngx_http_auth_basic_module.c
@@ -137,7 +137,7 @@
 
     if (rc == NGX_DECLINED) {
 
-        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
+        ngx_log_error(NGX_LOG_INFO, r->connection->log, 0,
                       "no user/password was provided for basic authentication");
 
         return ngx_http_auth_basic_set_realm(r, &realm);