STM32L1 HAL

~~The led blink app is not working yet, trying to figure out what's wrong.~~
The app is working, somehow only if the delay is less than 50, but the driver is mostly operational.
Please get rid of this. There's no pinmap for stm32l1 yet, and having configs structures is deprecated way to do things (they are not optimised away as good as we anticipated initially). The way to structure Pin API is to follow usual rust struct creation, e.g. renaming PinConf to Pin and providing a `new` method similar to `pub fn new(port: Port, pin_index: u8, function: Function, gpiodir: Option<::hal::pin::GPIODirection>) -> Pin`.

Pin functionality is implemented by `::hal::pin::GPIO` trait.