Fitbit node.

A useful first node. With an example flow included below.
-Mark

````
[{"id":"89a44cf.f765bb","type":"function","name":"","func":"var sleep = msg.payload.sleep[0];\nif (sleep.duration < 6.5*60*60*1000) {\n   msg.payload = \"Grumpy due to insufficient sleep!\";\n} else if (sleep.efficiency < 95) {\n   msg.payload = \"Grumpy due to reseless sleep!\";\n} else {\n   msg.payload = \"Cynical and sarcastic despite good sleep.\";\n}\n\nreturn msg;","outputs":1,"x":434,"y":154,"z":"fc90eb46.036f18","wires":[["84542d26.7babd"]]},{"id":"84542d26.7babd","type":"debug","name":"","active":true,"console":"false","complete":"false","x":653,"y":156,"z":"fc90eb46.036f18","wires":[]},{"id":"9736069d.68c9f8","type":"inject","name":"","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"x":103,"y":194,"z":"fc90eb46.036f18","wires":[["83eebb92.7c1148"]]},{"id":"83eebb92.7c1148","type":"fitbit","fitbit":"","name":"","dataType":"sleep","x":269,"y":188,"z":"fc90eb46.036f18","wires":[["89a44cf.f765bb"]]}]
````