Support new Google Fit health data types (blood glucose, etc)

[sgilroy]

Support new Google Fit health data types (blood glucose, etc)

[dariosalvi78]

Thanks for letting me know. It was under the radar and it's definitely good news. Consider it in the roadmap.

Warning
In the next release I am going to break the current interface for blood glucose.
Blood glucose will be represented by an object like this:

{ glucose: 5.5, meal: 'breakfast', sleep: 'fully_awake', source: 'capillary_blood' }

In Android it is already an object (see commit), I will need to change the iOS code too to reflect this decision.