raspberry piの不要パッケージを削除する

http://variedtastefinder.jp/blog/?p=742

sudo apt-get autoremove dillo netsurf-gtk netsurf-common mplayer libraspberrypi-doc debian-reference-en debian-reference-common xpdf ed nano sonic-pi scratch wolfram-engine minecraft-pi dbus triggerhappy
sudo apt-get autoremove
sudo rm -rf /usr/games