Update examples w/ cleaner serial code

We can simplify connecting to a device in all the examples with:

```python
import serial.tools.list_ports

# Open serial connection with the first Valve Controller.
com_port = None
ports = serial.tools.list_ports.comports()
for port, desc, hwid in sorted(ports):
if desc.startswith("lickety-split"):
print("{}: {} [{}]".format(port, desc, hwid))
com_port = port
break
device = Device(com_port)

```