Test uploads

[per1234]

Obviously it's not possible for Travis CI to upload to actual hardware and thus the upload process will always fail but problems with a hardware package could output warnings or cause the process to fail before the upload tool is started. If I can parse the output to detect these issues it could give a reasonable idea of any problems with a hardware package relating to uploads.

Errors/warnings to detect:

• avrdude: Can't find programmer id (see "Slow" programmers not recognized MCUdude/MicroCore#22 (comment))
• avrdude: can't open config file - missing avrdude.conf
  • Produces the additional warning: avrdude: error reading system wide configuration file