New book import should not reuse non-specific author records

### Description

The importer conflated two different authors because it wasn't appropriately cautious about not reusing author records which consist only of two names without any dates or other supporting evidence.

The bad data came from poor cataloging by the San Francisco Public Library, but we need to screen imports for quality. The author name was cataloged two different ways in the MARC record, providing a hint as to both trouble and the correct author record.

### Relevant url?
https://openlibrary.org/books/OL26953710M/Embers_of_war

### Expectation
Importers reject low quality data and not make OpenLibrary database worse than it already is.

### Stakeholders
@hornc