Added wpvulndb links

This PR adds some Links for Wordpress modules to https://wpvulndb.com/

Example output:
```
msf exploit(wp_google_document_embedder_exec) > info

       Name: WordPress Plugin Google Document Embedder Arbitrary File Disclosure
     Module: exploit/unix/webapp/wp_google_document_embedder_exec
   Platform: PHP
 Privileged: No
    License: Metasploit Framework License (BSD)
       Rank: Normal
....................................
References:
  http://cvedetails.com/cve/2012-4915/
  http://www.osvdb.org/88891
  http://secunia.com/advisories/50832
  https://wpvulndb.com/vulnerabilities/6073
```