Don't load application from flash after timeout, makes it work for
long ssh connection times when the raspi has no DNS and produces DNS
timeouts too long for the bootloader. Note that this needs a new icosoc
(at the time of this commit).
Biggest problem was definitions in rtimer_arch.h -- we have a 16-bit
rtimer_clock_t so this was overflowing and not working. Therefore most
delays in the radio implementation didn't work.
