Bind `other-window' to M-o

Suggested here:
http://www.masteringemacs.org/articles/2014/02/28/my-emacs-keybindings/
Always switch to buffer in new window

The default file and buffer switching methods for ido will raise a frame
if the buffer is already present somewhere else. With `selected-window',
the buffer is always shown in the current window, which behaves better
with multiple screens.