network-util doesn't handle NULL values

[atmathis]

Issue encountered when when apparent null value is collected by the network-util. Error message below (1200 into 5000+ results processed).

Traceback (most recent call last):
File "network-util.py", line 370, in
sys.exit(main())
File "network-util.py", line 357, in main
domain=args.domain)
File "network-util.py", line 158, in process_search
dst_ip = ipaddress.ip_address(netconn.remote_ip)
File "/usr/lib/python3.5/ipaddress.py", line 54, in ip_address
address)
ValueError: '' does not appear to be an IPv4 or IPv6 address

[crahan]

Hi @atmathis, I've submitted a pull request to help fix this issue here: #15