Add detection code MS Office

[SeeRM #8413] Add detection code for MS Office XP, 2003, 2007, 2010, and 2012.

Here's how to test this:

- [ ] Dump the detection code to /tmp/addons.js using msfconsole:

```
$ msfconsole -q
msf > irb
[*] Starting IRB shell...
	
>> File.write("/tmp/addons.js", ::Rex::Exploitation::JavascriptAddonsDetect.new)
=> 1086
```

- [ ] Create the following html file and the save it as /tmp/test.html:

```
<script src="addons.js"></script>
<script>
var v = window.addons_detect.getMsOfficeVersion();
if (v == null) {
	document.write("Office not installed or not enabled");
}
else {
	document.write("You are using Office " + v);
}
</script>
```

- [ ] Start a web server under directory /tmp:

```
$ ruby -run -e httpd /tmp/ -p 8181
```

- [ ] And now you're ready to test, make sure you're using Internet Explorer and browse to: http://[your ip]:8181/test.html. You should try to test the following setups: Office 2012 , Office 2010, Office 2007, Office 2003, Office XP, and an IE+Windows setup without Office installed.