Rework of trial versus non-trial installs

[obilodeau]

We can only specify one product key in the config file. I'm going to rework this so that we can have keys for all versions of Windows.

Also, since the ISOs are different (the ones for Windows 7 are at least) I'm going to split this out in different profiles.

Right now config file would look like this:

...
    "product_keys": {
        "win7_pro_x86": "XXXXX-XXXXX-XXXXX-XXXXX-XXXXX",
        "win7_pro_x64": "XXXXX-XXXXX-XXXXX-XXXXX-XXXXX",
    },
...