Update the troubleshooter

[PeterJCLaw]

Issues I spotted:

• the Ruggeduino route has the question "Is the Ruggeduino connected to the Power Board via an appropriately connected USB Hub?" which doesn't make sense
• the Ruggeduino route doesn't offer anything for the case where having a Ruggeduino in the loop causes the ODROID not to boot (which has been observed when there's a bad USB stick plugged in)
• there's no route at all for the ODROID
• the Servos route suggests that you can test a Servo using the WiFi, yet as far as I know there isn't a manual interface there

[PeterJCLaw]

We should encourage trying another USB stick if teams have issues. At least srobo/tasks#278 found a USB stick issue which had originally looked like a ruggeduino issue, so that's worth including explicitly. It may also be worth also suggesting a new USB stick as a generally useful step too.