STK500v2: Retries for reading from serial
STK500v2: Retries for reading from serial

This would normally not fly at all but we give it a pass here since we
only use that module for auto detection anyhow (and probably not for
much longer since that approach is simply too error prone).

Adapted from

  https://github.com/foosel/OctoPrint/issues/2138#issuecomment-334117910

by @dtynan.

Solves #2138 until I come up with something better

Jaesin/OctoPrint,Jaesin/OctoPrint,foosel/OctoPrint,Jaesin/OctoPrint,Jaesin/OctoPrint,foosel/OctoPrint,foosel/OctoPrint,foosel/OctoPrint