Added xfce to default packages, changed chromium package name

packages

-awesome vim vim-gui-common vim-nox git tig radiotray chromium-browser thunar
+awesome vim vim-gui-common vim-nox git tig radiotray chromium thunar
 gmail-notify numlockx htop mosh mupdf
 
+xfce4 xfce4-power-manager xfce4-screenshooter
+
 ranger gimp meld imagemagick curl bpython gparted tree graphviz realpath
 
 python-tornado pyflakes pep8 feh python-numpy python-scipy python-pygame