Additional Disk Functionality For vmware-iso builder

Using two disks in a VM is not an uncommon situation and a few other people have showed interest in a method that works for vmware builder. 

Adding additional disks to your VM can be done by adding the "add_disks" property as shown:

``` 
"add_disks": [
			["disk1", 100000, 0],
			["disk2", 100000, 0]
],
```
Each array represents one disk and it's parameters. The parameters are disk name, size, and disk type, respectively.