Convert windows.py module into a package

As the windows module got bigger and bigger we had to break it into more files
Add sysprep params before init is executed

In add_sysprep_param __init__ decorator, add the sysprep parameters
before executing the init function. This is needed if we want to be
able to access the sysprep_params dictionary from within __init__.
Move windows.py module inside the windows package
windows: Move code from Windows class to VM

Move all helper methods that control the Winodows VM from Windows to
VM class
windows: spit do_sysprep to reduce complexity

Add a new _exec_sysprep_tasks method that is called by do_sysprep and
hosts the actual code for executing the system preparation tasks
windows: Add a new registry module in windows

This modules hosts the Registry class which contains all the registry
manipulation code previously hosted under the Windows class