* Added HTTPUpdate class for downloading sketches from a server
* Added HTTPUpdate class for downloading sketches from a server
* Added HTTPUpdate to CMakeLists.txt
* Change ESP8266 class references to ESP32 for httpUpdate.ino example
* Change ESP8266 class references to ESP32 for httpUpdate.ino example. setLedPin() commented out because not all boards support LED_BUITLIN
* Added check to handle mixup of old and present api properly
* Correct HTTPClient::setTimeout() to convert milliseconds to seconds. Correct WiFiClient::setTimeout() to call Stream::setTimeout() with seconds converted back to milliseconds. Remove inproper checks for _insecure.
* Added small comment because it looked like the Travis build did not finish
* Add example to update ESP32 via SD card
* Delete update.bin from sd upon finishing update
* remove precompiled binary from example
* Check whether update.bin is a file
