In Terminal:

sudo nano /etc/inittab

Scroll down to:

1:2345:respawn:/sbin/getty 115200 tty1

and change to

#1:2345:respawn:/sbin/getty 115200 tty1

Under that line add:

1:2345:respawn:/bin/login -f pi tty1 </dev/tty1 >/dev/tty1 2>&1

Ctrl+X to exit, Y to save followed by enter twice