Fix hidapi interface. Return all available boards. Use USB path instead of serial number to identify board.
Update flash_nrf51822.py.
Use actual offset 0x16000.
Add "erase", "offset" and "skip" options for binary file for flexible operations.
Add "list" command line option to list available boards.
Add boardId to MbedBoard.listConnectedBoards() method.
Merge pull request #60 from anpilog/fix_hidapi_interface

Fix hidapi interface