py: better error handling, don't close connection on all errors
added magicUpload and magicPin (untested)
web2serial.js: only_devices_with_desc
added js/demo-magicshifter
Merge remote-tracking branch 'origin/magicshifter'

* origin/magicshifter:
  added magicUpload and magicPin (untested)
demo-magicshifter works
renaming demo-magicshifter
demo-magicshifter: buffered response, ui minim