Steps to install the UniFi controller on Ubuntu 16.04.  Note that the package depends on JRE7, so we must add the ppa repo to apt.

echo "deb http://www.ubnt.com/downloads/unifi/debian stable ubiquiti" > /etc/apt/sources.list.d/ubnt.list
apt-key adv --keyserver keyserver.ubuntu.com --recv C0A52C50

sudo add-apt-repository ppa:openjdk-r/ppa
sudo apt-get update

sudo apt-get install unifi