fixed byte order for ieee802.15.4 frame
correct byte order for IPv6 length field
correct byte order for UDP length field
Fix sixlowpan dependencies
Merge pull request #293 from authmillenon/fix_sixlowpan_dependencies

Fix sixlowpan dependencies
Merge pull request #259 from OlegHahm/ieee802154_frame_byteorder

fixed byte order in network stack