Add progress message

[steffilazerte]

Add progress message to weather_html() under verbose conditions. This will act like a progress indicator for large downloads, so users can see that things are progressing.

[boshek]

httr::progress() might do the trick here.

[steffilazerte]

That will work for single downloads, but the really long ones are where it downloads multiple files. I don't think this would apply to that scenario, right?

Best would be if purrr had progress bars, or alternatively, maybe this solution using the progress package: https://stackoverflow.com/a/46517585