More errors messages (#353)

Add more error messages for HTTP errors/SSL errors

include/ui_strings.h

@@ -130,6 +130,9 @@ typedef struct {
     const char *parental_fail;
     const char *zip_not_found;
     const char *generic_httpc_error;
+    const char *http_timeout;
+    const char *http_no_network;
+    const char *http_ssl_error;
     const char *http303_tp;
     const char *http303;
     const char *http404;