Search URLs for drop-down contextual menu

To start, I've added some elements to drop-down menu for IP search:
- VirusTotal search by IP
- reverse whois (DomainTools, CentralOps)
- search engines (Google, Bing)
- ranking sites (Alexa)
- blacklists (ZeusTracker, MDL, Google SafeBrowsing)

```
+-------------------+------------------------------------------------------------------+
| Alexa             | http://www.alexa.com/siteinfo/${var}                             |
| Bing              | https://www.bing.com/search?q=ip%3A${var}                        |
| CentralOps        | http://centralops.net/co/DomainDossier.aspx?addr=${var}          |
| DomainTools       | http://whois.domaintools.com/${var}                              |
| Google            | https://www.google.com/search?q=${var}                           |
| MalwareDomainList | http://www.malwaredomainlist.com/mdl.php?search=${var}           |
| SafeBrowsing      | https://www.google.com/safebrowsing/diagnostic?site=${var}       |
| VirusTotal        | https://www.virustotal.com/en/ip-address/${var}/information/     |
| ZeusTracker       | https://zeustracker.abuse.ch/monitor.php?search=${var}           |
+-------------------+------------------------------------------------------------------+
```

I can add more if you have something to suggest.