time as python datetime in query result

[aewallin]

a helper function that would produce python datetimes from the influxdb time-stamp would be useful.

I tried cutting the time text-field at microsecond resolution, but it seems trailing zeros are not stored in influxdb so the returned time-string can have variable precision (milli, micro, nano) with anything from 0 to 9 digits after the decimal point.

a further enhancement would be to provide a datetime subclass with nanosecond resolution.