Ubuntu change to dark theme

sudo add-apt-repository ppa:noobslab/themes  #just for Ubuntu 14
sudo apt-get update
sudo apt-get install ambiance-dark

sudo add-apt-repository ppa:noobslab/themes
sudo apt-get update
sudo apt-get install arc-theme

sudo add-apt-repository ppa:tualatrix/ppa
sudo apt-get update
sudo apt-get install ubuntu-tweak

sudo add-apt-repository ppa:ravefinity-project/ppa  #current for me

sudo apt-get update

sudo apt-get install vivacious-colors-gtk-dark
                     

or

sudo apt-get install unity-tweak-tool #need to re-start

resources:
Dark themes
http://askubuntu.com/questions/454372/dark-gtk-theme-for-ubuntu-14-04