Add warnings based on breaking spec changes from earlier version of json table schema

[ldodds]

id became name
label became title

This was in earlier version but there are some packages using this still.

[ldodds]

Decided to leave this unimplemented: better to be clear about what fields are required, than trigger an error or warning about these older properties. Its clearer as to what action must be taken and doesn't make it seem as if packages designed to work with older tools are invalid.