Update declarations for SP800-53

[wendellpiez]

User Story:

As an OSCAL user and developer, I can see some inconsistency between artifacts and how they are represented. In particular, I notice that since recent changes (Sprint 11), the SP800-53 catalog does not presently validate against its (own) declarations, since its tagging/contents have changed (#175) in detail. (It validates against the Catalog XSD but that is a different matter.)

Goals:

The SP800-53 catalog is complete, correct and internally consistent.

Dependencies:

The catalog and its location must be stable.

Acceptance Criteria

• SP800-53 can be shown to be valid to its declarations via the Schematron.
• The data looks good, clean and correct. In particular, recent changes regarding handling of label properties (formerly 'names') are reflected in both the data, and its declarations.
• Its validation can be shown to be effective, for example by testing broken data and confirming the correct error messages are returned, showing the anomalies in the data.

[wendellpiez]

Since commit 7be48c86daccbcbe96a4a34d54f33a8c8a8f1ac4 the SP800-53 catalog is now valid again to its declarations file. However, this Issue may need to be revisited in view of possible changes to the catalog resulting from #218.