list vs int tpyes for metric= and channel= in measurements_list and WriteOnlyMeasurementSerializer

[alexhutko]

writing measurements allows using channel_id and metric_id as solo ints:
measurement = WriteOnlyMeasurementSerializer(metric=metric_id, channel=channel_id, value=my_value...

reading measurements requires them to be in a list even if that list has only one element:
api_measurement_measurements_list( metric=[metric_id], channel=[channel_id], starttime=T1, endtime=T2)

For the reading of measurements, this is a different behavior than before when solo ints were accepted. Was this because it was allowing slop before and shouldn't have accepted "metric=metric_id"?

When I add multiple values to the list, e.g. metric = [84,85,86], I only get returned the measurements from the last element in the list, in this case metric_id = 86. This leads me to think only one channelID and one metricID are accepted. If that is true, we should change this to require solo ints rather than [int]. If it should return measurement values for 84,85,and 86, then there's a bug.

Let me know if I'm totally off my rocker and missing something...