Support better error messages for metacard creation issues

[rzwiefel]

Instead of silently working and assuming or silently dropping when creating metacard attributes, we should work to return helpful error messages of what went wrong and why for consumers to know why an attribute wasn't included or such.

One possible implementation could be by changing the CatalogMethods::getAttribute method to somehow return more information (possibly a third piece of information?) on if attributes were found to have issues.