Add powerline

Hi Dieter,

here is my install-powerline.sh script to install the patched powerline font and the powerline.js module. After that you have to restart the desktop or logout + login. After that the terminal shows the powerline.
The trick was to set the locale to en_US.utf8.

I also tried to integrate everything into the Vagrantfile. vagrant pristine -f is running at the moment. I don't know where npm will install the powerline.js for the .bashrc heredoc. So the Vagrantfile is only a first try.

Stefan