cpu/nrf51822: fixed gpio driver
boards: added LED macro for pca1000 & yunjia-nrf
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