add try/except for gaierror to address #97 (#98)

mac OS upgrades can lead to machines unable to get IP from hostname.  this is a fix to revert to using 'localhost' in case of a gaierror from socket.gethostbyname

icepyx/core/Earthdata.py

@@ -47,8 +47,12 @@ def __init__(
  def _start_session(self):
  #Request CMR token using Earthdata credentials
  token_api_url = 'https://cmr.earthdata.nasa.gov/legacy-services/rest/tokens'
- hostname = socket.gethostname()
- ip = socket.gethostbyname(hostname)
+ #try initially with machine hostname
+ #revert to using localhost if gaierror exception
+ try:
+ ip = socket.gethostbyname(socket.gethostname())
+ except:
+ ip = socket.gethostbyname('localhost')
 
  data = {'token': {'username': self.uid, 'password': self.pswd,\
  'client_id': 'NSIDC_client_id','user_ip_address': ip}