NCDC is now NCEI

[EthanGoldman]

Describe the bug
I briefly got a runtime error about the NCDC FTP server (ftp.ncdc.noaa.gov) not responding. When I went to check on the web, I discovered that NCDC changed their name to NCEI, and they now show a link to download data from their ftp server at ftp://ftp.ncei.noaa.gov/pub/data/noaa/

NOTE: this turned out to be a transient error, and the next time I ran the function I got a successful response with data. However, it might be safer for the future if we change the ftp address to match their new one.

To Reproduce
Steps to reproduce the behavior:

1. Run station.load_isd_hourly_temp_data(start_date, end_date)

Expected behavior
Data comes back with no errors