Add explicit timezone (UTC) to datetime objets

[supermanzer]

Update the date/time parsing and creation code to explicitly add a timezone of UTC to the datetime objects returned.

Motivation:

  I'm Sunni, and I use NDBC data for model validation.

I'm writing because I want to verify the time zone of the data I'm pulling.

I read on the NDBC Measurement Descriptions and Units page: https://www.ndbc.noaa.gov/measdes.shtml that both Realtime and Historical files show times in UTC only.

I took a look at the NDBC.py code, and it looks like the data I'm pulling (stdmet) is coming from files that are accessed.

If that's the case, I would imagine the remark about Realtime and Historical files (UTC) applies to the data I'm pulling.

I just want to confirm for my own use and for the benefit of others.

Thanks!

Originally posted by @piratepheasant in #22 (comment)