Handle connection errors

[bortok]

Starting port status discovery for 172.20.100.33
Traceback (most recent call last):
File "/Users/albortok/Documents/00_Projects/ix/ixvision/ixvision-zta/ixvztp", line 134, in
discover_ports(host, port, username, password, keyword)
File "/Users/albortok/Documents/00_Projects/ix/ixvision/ixvision-zta/ixvision_ztp_port_discovery.py", line 24, in discover_ports
nto = NtoApiClient(host=host_ip, username=username, password=password, port=port, debug=True, logFile="ixvision_ztp_debug.log")
File "/Users/albortok/Documents/00_Projects/ix/ixvision/ixvision-zta/ixia_nto.py", line 49, in init
response = self.connection.urlopen('GET', '/api/auth', headers=self.password_headers)
File "/Users/albortok/Documents/00_Projects/ix/ixvision/lib/python2.7/site-packages/urllib3/connectionpool.py", line 667, in urlopen
**response_kw)
File "/Users/albortok/Documents/00_Projects/ix/ixvision/lib/python2.7/site-packages/urllib3/connectionpool.py", line 667, in urlopen
**response_kw)
File "/Users/albortok/Documents/00_Projects/ix/ixvision/lib/python2.7/site-packages/urllib3/connectionpool.py", line 638, in urlopen
_stacktrace=sys.exc_info()[2])
File "/Users/albortok/Documents/00_Projects/ix/ixvision/lib/python2.7/site-packages/urllib3/util/retry.py", line 398, in increment
raise MaxRetryError(_pool, url, error or ResponseError(cause))
urllib3.exceptions.MaxRetryError: HTTPSConnectionPool(host='172.20.100.33', port='8000'): Max retries exceeded with url: /api/auth (Caused by NewConnectionError('<urllib3.connection.VerifiedHTTPSConnection object at 0x105dd6750>: Failed to establish a new connection: [Errno 61] Connection refused',))