Add windows userdata support

* refactor cloudinit packages to include support for windows userdata
* fix NewMachineConfig to store corect paths when on windows
remove global CloudInitOutputLog
Merge pull request #579 from gabriel-samfira/add-windows-userdata

Add windows userdata support

This is the same as #189 but with a fix for [bug-1359333](https://bugs.launchpad.net/juju-core/+bug/1359333)

Tests pass locally, ran bootstrap from Windows, created staging branch and successfully deployed both windows and ubuntu.