azmetr 0.3.0

• az_hourly() now accepts dates for start_date_time and end_date_time
• Improved messages regarding what date/time ranges are being queried and returned by data retrieval functions.
• az_hourly() now returns data from the previous hour when start_date_time and end_date_time are not supplied rather than returning the previous day of hourly data.
• azmet is now much more verbose, printing messages about which data are requested and which data are returned.
• Added an option "azmet.print_api_call" which, when set to TRUE prints the HTTP request sent to the API—for debugging purposes.
• Fixed a bug that caused an error when data was requested from all stations but some stations didn't have data for all variables.
• Requests for data before January 1, 2021 now error, since these data are not on the AZMet API (yet).