Upgrade KeepKey for new libagent code

Add get_public_node for KeepKey

libagent/device/keepkey_defs.py

@@ -9,6 +9,9 @@ from keepkeylib.transport_hid import HidTransport
 from keepkeylib.transport_webusb import WebUsbTransport
 from keepkeylib.types_pb2 import IdentityType
 
+get_public_node = Client.get_public_node
+sign_identity = Client.sign_identity
+Client.state = None
 
 def find_device():
     """Returns first WebUSB or HID transport."""