Make examples in v2.0 spec validate without warnings

[zimeon]

In v1.1 we have:

• https://ocfl.io/1.1/spec/#example-minimal-object -- GOOD
• https://ocfl.io/1.1/spec/#example-versioned-object -- GOOD
• https://ocfl.io/1.1/spec/#example-object-diff-paths -- warning because of missing message
• https://ocfl.io/1.1/spec/#example-bagit-in-ocfl -- Inventory is good but do we have the data to build the example as a fixture?
• https://ocfl.io/1.1/spec/#example-moab-in-ocfl -- warnings because of missing user and message, and intentionally because the version directories are zero padded (BUT ERROR because the head and the keys in the versions block are not zero-padded as they should be to match the version directories). NEED TO FIX THIS and the moral of the story is that we should have validated a fixture object for any example