"Memory Leaks" - Stops working after some requests

[h4km4k]

It took me some time to realize it (thougt it was a problem with stable current).

By adding

  Serial.println(ESP.getFreeHeap());
  Serial.println(ESP.getHeapFragmentation());

to the code i saw the problem is a memory leak.

I fixed it by changing from String to C-String. (see my pull request)