Feature/go hci v2

This commit replace the c-shim with go-hci.

Note:
It requires linux kernel v3.14+ for the new USER_CHANNEL of HCI socket.
When a device is opened with user channel, it requires exclusive usage of the HCI interface.
So the HCI interface must be in "DOWN" status, or -EBUSY is returned.

ex: sudo hciconfig hci0 down

Revision history:
v0: 9225a4f
v1: dc97e446206d4fae540cfd2ba8c764a720056951