cpu/nrf51822: fixed gpio driver
boards: added LED macro for pca1000 & yunjia-nrf
udp: fix byte order in sockaddr6_t

udp_recvfrom wrote the sender port number in host byte order into the
provided sockaddr6_t. Because all send functions expect the port number
in network byte order this introduces a superfluous conversion step in
case one wants to reuse the address for replying.

closes #1406
examples: add extern "C" to header `rpl_udp.h`
Fixes when a packet is not for me, but an interface is defined.
Merge pull request #1796 from RIOT-OS/ip_is_our_fix

Fixes when a packet is not for me, but an interface is defined.
net: Initial import of a packet wrapper for priority_queue
Merge pull request #1640 from authmillenon/packetqueue

net: Initial import of a packet wrapper for priority_queue
Merge pull request #1790 from BytesGalore/extern_C_in_headers_examples

examples: add extern "C" to headers
sys/net/pktqueue: fix doxygen
Merge pull request #1798 from LudwigOrtmann/pktqueue-doxygen

sys/net/pktqueue: fix doxygen
Merge pull request #1795 from sgso/byte-order-udp-sockaddr

udp: fix byte order in sockaddr6_t
Merge pull request #1720 from haukepetersen/fix_nrf_gpio

cpu/nrf51822: fixed gpio driver
Merge pull request #1722 from haukepetersen/fix_nrf_leds

boards: added LED macro for pca1000 & yunjia-nrf
Initial working commit
Style, typo, header, coding conventions fixes
root_status function renamed and routing entries now global variables.
Unified IPv6 sending function to handle optional fix next_hop
Merge conflict with ip.c resolved.