ad dbus and psutil package to debian deps

Not all debian derivatives pull in dbus and psutil by default (eg crouton trusty target)

README.md

@@ -23,7 +23,7 @@ A precompiled version is available at http://koti.kapsi.fi/~kliment/printrun/
 
 You can run Printrun directly from source, as there are no packages available yet. Fetch and install the dependencies using
 
-1. `sudo apt-get install python-serial python-wxgtk2.8 python-pyglet python-tornado python-setuptools python-libxml2 python-gobject avahi-daemon libavahi-compat-libdnssd1`
+1. `sudo apt-get install python-serial python-wxgtk2.8 python-pyglet python-tornado python-setuptools python-libxml2 python-gobject avahi-daemon libavahi-compat-libdnssd1 python-dbus python-psutil`
 
 ### Fedora