Updater: Better flow for performing updates; added MD5 validation.

include/updater.h

@@ -1,8 +1,10 @@
 #pragma once
 
+#include "http_client_wrapper.h"
+
 class Updater {
 public:
-	static void run();
-	static bool do_update(int cmd, String url);
-	static void update_spiffs();
+	static void run(uint16_t spiffs_version = 0);
+	static bool do_update(int cmd, String url, String expected_md5);
+	static bool read_line(String* dst, HTTPClientWrapper* http, String expected_key);
 };