Merge pull request #2 from sandys/master

changes to CMakeLists done. no sbrk error.
update gitmodules with new BLE_API mirror
Merge branch 'master' of https://github.com/janekm/mbed-nrf51-gcc-test
updated BLE_API
Merge branch 'new_branch_name'
updated gitmodules for nrf51822
intermediate commit - not building yet