[init] Group related files together
[init] Fix Finders's annoying update problem

On Mac OS X, `Finder` has this annoying problem that it won't show
immediately the changes made to files from within other apps. If, for
example, a file is created, removed or modified from an app such as
`Terminal`, `Gimp` etc, `Finder` won't reflect the changes, because
it won't:

 * show the newly created files
 * remove the recently deleted files
 * update the file previews
 * update file information such as file size

This commit solves the problem by providing:

 * a script that forces Finder to continuously update it's internal
   information about the visible files (files shown in the open windows
   and on the desktop)
 * a way to make the script automatically start after user login, using:
   defaults write com.apple.loginwindow LoginHook /path/update_finder.sh

Close alrra/dotfiles#1.