Updated quickguide about push.sh

Doing:
rosrun object_recognition_core push.sh 
Was getting:
/opt/ros/fuerte/share/object_recognition_core/bin/web_ui/push.sh: 4: /opt/ros/fuerte/share/object_recognition_core/bin/web_ui/push.sh: couchapp: not found

So added a comment that you need couchapp for it :)