added spark core board
auto_init: adapt auto_init for cc110x devices
rpl_udp: Addresses must only be 8-bit with cc110x
rpl_udp: optimize error handling for set command
Merge pull request #1728 from mehlis/add_board_spark_core

added spark core board
Merge pull request #1878 from authmillenon/rpl_udp-16bit-addr

rpl_udp: Addresses must only be 8-bit with cc110x