BUG | Canvas shell cosmetics

[idncsk]

Couple of things to quick-fix

• sessions submenu naming is rubbish
• We should call canvas_disconnect on error (was already the case, no idea why why why I removed it)
• Add data abstraction API support (may require canvas-server update too)
  • context list , for example context list notes => json of notes
• Add a configuration option to print only a subset of the metadata or json, (--format json if we choose to not default to a full json) => nvm, this one will be more complicated, will be a separate ticket