Build on top of universal API

[techtonik]

urwid is only supported for Linux through series of low level fcntl calls.

  File "conjureup\app.py", line 18, in <module>
    from ubuntui.ev import EventLoop
  File "C:\Python36\lib\site-packages\ubuntui\ev.py", line 15, in <module>
    class EventLoop:
  File "C:\Python36\lib\site-packages\ubuntui\ev.py", line 22, in EventLoop
    'screen': urwid.raw_display.Screen(),
  File "C:\Python36\lib\site-packages\urwid\raw_display.py", line 89, in __init__
    fcntl.fcntl(self._resize_pipe_rd, fcntl.F_SETFL, os.O_NONBLOCK)
NameError: name 'fcntl' is not defined

This is not portable.