i got my HomeBridge running with autostart @reboot (rpi) :D
I used PM2 instead of forever. If you follow the instructions below, it will autostart HomeBridge after a reboot of you pi...
sudo npm install pm2 -g
cd ~/homebridge/
pm2 start app.js --name HomeBridge
pm2 save
pm2 startup raspberry
sudo su -c "env PATH=$PATH:/usr/local/bin pm2 startup raspberry -u pi"
sudo chmod +x /etc/init.d/pm2-init.sh
Edit /etc/init.d/pm2-init.sh so that export PM2_HOME="/home/pi/.pm2" (was export PM2_HOME="/root/.pm2" but this causes errors)
sudo update-rc.d pm2-init.sh defaults
Reboot and check proceslist...
sudo reboot
pm2 list
Should something look like...
┌────────────┬────┬──────┬──────┬────────┬─────────┬────────┬────────────┬──────────┐
│ App name │ id │ mode │ pid │ status │ restart │ uptime │ memory │ watching │
├────────────┼────┼──────┼──────┼────────┼─────────┼────────┼────────────┼──────────┤
│ HomeBridge │ 0 │ fork │ 9092 │ online │ 0 │ 0s │ 9.113 MB │ disabled │
└────────────┴────┴──────┴──────┴────────┴─────────┴────────┴────────────┴──────────┘
Enjoy!