cd ~
wget https://github.com/fg2it/phantomjs-on-raspberry/raw/master/rpi-2-3/wheezy-jessie/v2.1.1/phantomjs
chmod 755 phantomjs
sudo chown root: phantomjs
sudo mv phantomjs /usr/share/grafana/tools/phantomjs/
However, as I didn’t upgrade grafa yet, I don’t know if the path exists per default, so maybe you have to create the folder first:
sudo mkdir -p /usr/share/grafana/tools/phantomjs