gpio_python: Re-write external python script

Signed-off-by: Alistair Francis <alistair23@gmail.com>
stm32f405_gpio: Move the GPIO header

Signed-off-by: Alistair Francis <alistair23@gmail.com>
stm32f405_gpio: Change some equality comparisons

Signed-off-by: Alistair Francis <alistair23@gmail.com>
stm32f405_gpio: Tidy up the client server

Signed-off-by: Alistair Francis <alistair23@gmail.com>