thumbnailer for directories

[Daniel Godas <siro san gmail com>]

i made a thumbnailer for directories, it generates a view showing the
first mimetypes it finds inside the directory it is thumbnailing. I
filed a bug in bugzilla -> #153485

heres a link to the file if you want to try it
http://bugzilla.gnome.org/attachment.cgi?id=31854&action=view

PD: i included a simple Makefile so noone should have problems to compile it.