Doi Bug Fix (#659)

* ENH: AirNow API must have updating some algorithms.  What it's displaying now is what I would have assumed would be the closed reported station.

* ENH: Adding feature for users to be able to get the citation for a datastream.  Also adds text after data are done downloading from ARM to please reference the citation of the datastream

* ENH: Changing doi.org to just doi

* ENH: Moving into if loop for successful file generation

act/discovery/get_armfiles.py

@@ -163,6 +163,12 @@ def download_data(username, token, datastream, startdate, enddate, time=None, ou
                     print(f'[DOWNLOADING] {fname}')
                     open_bytes_file.write(data)
             file_names.append(output_file)
+        # Get ARM DOI and print it out
+        print(datastream, start_datetime, end_datetime)
+        doi = get_arm_doi(datastream, start_datetime.strftime('%Y-%m-%d'), end_datetime.strftime('%Y-%m-%d'))
+        print('\nIf you use these data to prepare a publication, please cite:\n')
+        print(textwrap.fill(doi, width=80))
+        print('')
     else:
         print(
             'No files returned or url status error.\n' 'Check datastream name, start, and end date.'