Add sleep analysis sample metadata at the query sample type result set

[Pickachu]

Hello!

First of all, thanks for the great plugin. Hope we will get support for all health kit data eventually, .o/

I'd like if the metadata field of sleep analysis were intentionally left out. if not it will be really good to have this field, since some apps add advanced useful data.

Here it is ignored when building the response from cordova Healthkit:

cordova-plugin-health/www/ios/health.js

Lines 243 to 256 in c2ff0a5

	opts.sampleType = 'HKCategoryTypeIdentifierSleepAnalysis';
	window.plugins.healthkit.querySampleType(opts, function (data) {
	for (var i = 0; i < data.length; i++) {
	var res = {};
	res.id = data[i].UUID
	res.startDate = new Date(data[i].startDate);
	res.endDate = new Date(data[i].endDate);
	if (data[i].value == 0) res.value = 'sleep.inBed';
	else if (data[i].value == 1) res.value = 'sleep';
	else res.value = 'sleep.awake';
	res.unit = 'activityType';
	res.sourceName = data[i].sourceName;
	res.sourceBundleId = data[i].sourceBundleId;
	result.push(res);

A sample of useful data added by AutoSleep, see the metadata field on Source Chain panel.

[dariosalvi78]

I wouldn't mind adding this information to the data returned, it is full of "juice". I am not sure how make this uniform across the API though. But to start from somewhere, we could maybe add the metadata object whenever available in iOS.

Would you mind sending a PR where you add the metadata to the returned object? (and please also add a line in the README to explain what happens)