Relay sensor historical data to client(s)

[jxmot]

Modify the socket.io server so that it will respond to requests for historical data. Clients will use the existing socket connection and issue a history request.

Major Tasks:

• Create a testing client that can display graphs of sensor data COMPLETE
• Modify this app so that it can receive and respond to requests from the client
  • Recognizes requests COMPLETE
  • Assembles a database query COMPLETE - retrieves sensor data, added new columns to config table for color selection
  • Runs the query and returns the result to the client COMPLETE

[jxmot]

Prototype chart app will be found in /chart after its branch is merged.

[jxmot]

Client side is here - https://github.com/jxmot/sensornet_chart