MailBox notification with ESP-01 and IFTTT

This code will make a single webhook call, and then enters in deep sleep.
Every time that the ESP-01 is reset will repeat this process.
Electrical connections are simple, supply the ESP with 3.3V and a switch between
reset pin and ground.
OTA (Over The Air) firmware upgrade process was also implemented, just place
the new bin file in a web server and a file including the firmware version.
If version differ from the one stored on the local virtual EEPROM the new firmware
will be pulled and installed.
Use ESP-01 with memory > 1MB
Arduino IDE was used

Libraries:
<ESP8266WiFi.h> - wifi with ESP8266
<ArduinoOTA.h> - OTA firmware update
<EEPROM.h> - non-volatile memory storage
<ESP8266httpUpdate.h> - http update
<ESP8266HTTPClient.h> - http call

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
version 2 as published by the Free Software Foundation.

Firmware: 1.0 - 08/2020
Autor: ArgusR <@argusro>