Upgrade the support for Open Badges 2 to support a real open badges 2 backpack.
Moodle can only talk to one backpack at a time, so after switching backpacks, users
will have to manually disconnect and then reconnect their backpack to the new one.
This commit combines several changes:
* Split classes into badges namespace
* Publish expiry data with a badge
* Publish badge alignments in badges exported to the backpack.
* Export the criteria for a badge to the backpack.
