Auto-update Docker image
It would be nice if dabuild would auto-update its Docker image every so often (maybe once a month?) as otherwise the updates inside the container will get longer and longer.
My suggestion is checking (with some docker magic) how old the image is, if it's older than 30 days then ask the user whether they want to update the image (then it would docker pull the new image and continue) or not, where the tool just continues and does the updates inside the container as it does at the moment