Poor handling of malformed EML metadata

[rogerdahl]

DeX relies on EML metadata correctly matching and describing the CSV table to be rendered. When there are errors or mismatches in the EML or CSV, it leads to hard to diagnose errors in DeX. See Ticket #79 for an example of this.

We have decided not to attempt to address this in DeX at this time, as it is something we want to address at a more general level with a new, unified congruence checker that can be used in all places where we ingest user generated metadata and data, including DeX, ezEML and the DataPortal.

Work on implementation for the unified congruency checker will be tracked in PEP-8.