Fixes for NRF51822:
- add options for gdb_server.py: SoftDevice flash protection, don't break at hard fault handler, correct resume procedure, add extra monitor command.
- mask interrupt when stepping. Required for NRF51. Otherwise GDB server can't step if any interrupt occured during halted state. In case of nrf51 with enabled BLE it happens all the time.
- fix nrf51 reset(), resetStopResume() functions.
- add nrf51 specific gdb_server server.
Fix 'mon help' commands in GDBServer. Cleanup after code review.
Align gdbserver options. Rename flash_protect_offset to flash_protect. Merge nrf51 gdb server.
Rename flash_offset to skip_bytes.
Merge pull request #62 from anpilog/update_nrf51822

A lot fixes for NRF51822. Make pyOCD usable with nRF51 CPU.