off by one error in checksum array?
sending: checking for successful publish
added Uno functionality
updated controller
Board specific tidy-up
moved more functionality to boards
moved sendData to boards

* sendData now up to boards, so that UNOs can split it up into
  several boards/sketches, whereas YUNs can keep all together.
+ removed SensorY from TestSensors setup in mainsketch, as it is
  set up to report several values per timestamp, but the TestSensor
  class doesn't, hence it didn't get accepted by the database.