Merge pull request #6121 from miri64/native/feat/zep_socket

boards/native/Makefile.dep

cpu/native/Makefile

cpu/native/include/native_internal.h

cpu/native/include/socket_zep.h

cpu/native/include/socket_zep_params.h

cpu/native/socket_zep/Makefile

cpu/native/socket_zep/socket_zep.c

cpu/native/startup.c

cpu/native/syscalls.c

examples/gnrc_border_router/Makefile

sys/auto_init/auto_init.c

sys/auto_init/netif/auto_init_socket_zep.c

sys/include/net/zep.h

tests/socket_zep/Makefile

tests/socket_zep/main.c

tests/socket_zep/tests/01-run.py