stm32f4: Document which discovery board the examples are for

Try and reduce a little confusion if we can.
Update the library to the newest version
example for MSC (Mass Storage Class) support
MSC: Use another PID to load correct drivers
Use libopencm3 coding style
stm32f4: drop dead code from usb example.

Presumably code that attempted to toggle a led, but it wasn't setup, and it's
not in any other examples.  Kill it for now.

Reported-by: stefanct on irc.
Update upstream library.
Update upstream library
Update library for new gpio_toggle
stm32/l1: lcd: example using the LCD
Update library to get spi fix
Merge remote-tracking branch 'upstream/master'

Conflicts:
	libopencm3