Mark 1 should auto upgrade, but there is a bug in 0.8.17 that prevents it to do so. We have a patch for that in form of a skill. https://github.com/MycroftAI/skill-platform-patch. To use the skill, ask Mycroft to download platform patch, then say
hey myrcoft... platform patch. You can also just type this into your Mark 1 command line.
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys F3B1AA8B which is pretty much what that skill does. Now your Mark 1 should check nightly to upgrade to the newest version. To manually install the newest version you can type in
sudo apt-get update && sudo apt-get install mycroft-core.
Hope that helps!