update dev install ubuntu in readme

Updated instructions so that it works with a sh file in a clena ubuntu
12.04 x64 environment

I hope that this helps others out.

changes

* add python-software-properties to python apt-get so  add-apt-repository works on x64
* added -y options to multiple install commands so it works in a shell file
* added initial apt-get update so that the install list is current
* removed virtualenv apt-get install and use pip virtualenvwrapper install instead