1.1.0 - raising error for failed downloads, changing image IDs in Figures, packing lists of objects, fixing empty image names

What's Changed

• raising a NonzeroReturnCode when download fails by @erickmartins in #81
• Making reference to image IDs not contained in a pack negative in Figures by @erickmartins in #84
• packing list of objects by @erickmartins in #85
• Readme update, test infra update by @erickmartins in #86
• using updated pytest interface by @erickmartins in #90
• dealing with empty image.name returned by showinf in prepare (also updating dependencies) by @erickmartins in #91

Full Changelog: 1.0.1...1.1.0