Fail properly if the profile is executed on a non-supported windows environment

[chris-rock]

The profile already restricts its usage to Windows. In case we cannot determine a proper fetcher, we get the following error:

libraries/windows_updates.rb:109:in `fetchUpdates': undefined method `fetchUpdates' for nil:NilClass (NoMethodError)
    from libraries/windows_updates.rb:58:in `all'

Handle those cases properly