Release 1834

The old Contact method had firstname and lastname but our new API model as first_name and last_name. As the MissingContact is used in its place in certain situations we need to have parity with the attribute names.

I'm leaving in the original attributes for now as other models still use that naming convention and I don't want to inadvertently break it elsewhere.

I'll go through and do a repo-wide rename of these attributes in a future PR.