Added shodan-hq.nse script

[glennzw]

New script to passively scan targets via ShodanHQ.

[fgeek]

Works okay for the output defined in description. By the way..

118     if (string.len(hostnames) > 0)
119     then
120         result = result .. " (" .. hostnames .. ")"
121     end

Looks like this:

| shodan-hq: Report for 91.232.154.65 (lime.kapsi.fi )

[dmiller-nmap]

Great! Made a few organizational changes and committed in r35694.

• renamed to shodan-api
• added external category
• added an API key check to avoid repeated queries with a bad key
• slightly different field names, dropped constant "STATE" column (always open)
• Avoid running on known private/reserved addresses
• Ensure target script arg is an IP address

Forgot to link this PR in the commit message, but it's 663271f