Fix icons for freedesktop standarts in python script

I've moved all icons/logos setup to python-program and use
http://www.pygtk.org/docs/pygtk/class-gtkbuilder.html#method-gtkbuilder--add-from-string
for set icons w/ xdg standarts w/ http://freedesktop.org/wiki/Software/pyxdg/
I see it causes no regressions.

Reference: http://code.google.com/p/scanmem/issues/detail?id=68

Signed-off-by: Igor Gnatenko <i.gnatenko.brain@gmail.com>