WyomingUpperAir Missing Station Information

[tkschuler]

wyoming.py fails with:

df = WyomingUpperAir.request_data(datetime(2012, 1, 1, 0), '82244')

This is because with the raw text on the server, Latitude is listed as '******' and can't be converted to a float. On further inspection, Longitude is missing, and Elevation is -9999.0 I've noticed this with multiple soundings in South America.

I think it would make the most sense to return None or Nan for Latitude, Longitude and Elevation when this problem arises.