Create heartBeat_device

This reads values from the Pulse Sensor Amped and sends them to the Agent.
Create heartBeat_agent

receives values from device and answers http requests from website
Create heartBeat_HTML

updates HTML page with information sent from agent
Refactored PulseSensor into a class
added states to the read() function
Merge pull request #19 from circuitFlower/patch-1

added states to the read() function
Merge pull request #17 from electricimp/circuitFlower-master

Refactored Pulse Sensor code