fix license headers in non-.c files

boards/arduino-due/include/board.h

boards/arduino-due/include/periph_conf.h

boards/avsextrem/include/board.h

boards/avsextrem/include/configure.h

boards/avsextrem/include/smb380-board.h

boards/avsextrem/include/ssp0-board.h

boards/chronos/include/board.h

boards/doc.txt

boards/msb-430-common/include/board-conf.h

boards/msba2/include/board.h

boards/redbee-econotag/include/board.h

boards/udoo/include/board.h

boards/udoo/include/periph_conf.h

boards/z1/include/board-conf.h

boards/z1/include/board.h

core/doc.txt

core/include/arch/atomic_arch.h

core/include/arch/hwtimer_arch.h

core/include/arch/io_arch.h

core/include/arch/irq_arch.h