Added I2C sensor support
Added support for I2C sensors:
- MAX44009, TSL2561, BH1750 (lux)
- BME280, BMP280 (temperature, pressure, and humidity(BME280 only)
- TCS34725 (color lux)
- AM2320 (temperature, humidity)
Added ST_Anything_I2C_ESP8266WiFi.ino example sketch to demonstrate how to use these new sensors.