Crashes with DeviceOS 2.0.0 due to missing return

[ScruffR]

int playLED() fails to return a value and starting with 2.0.0 this causes a SOS panic crash.

Adding return strtol(color, NULL, 0); at the bottom of this function should do the trick

https://github.com/particle-iot/xmastree/blob/master/src/firmware/xmastree.ino#L101

[wesleycombs]

Thanks @ScruffR - that did the trick.