NodeMCU Lua code for an ESP8266 garage door sensor
Based on code snippets from:
http://www.esp8266.com/viewtopic.php?f=19&t=1783
http://www.esp8266.com/viewtopic.php?f=19&t=1981
http://allaboutee.com/2015/03/24/es8266-text-messages-with-twilio-and-nodemcu/