Improve tests for normalization

[gaurav]

Most normalization methods start by deep cloning the object being normalized -- this means that if we were to add new properties to those methods, they would be included in the normalized object:

• CitationWrapper
• PhyxWrapper
• PhylorefWrapper
• PhylogenyWrapper

Some of them, however, specifically pick the properties/keys needed to construct normalized versions of taxon concepts, taxon name and specimen:

• TaxonConceptWrapper
• TaxonNameWrapper
• SpecimenWrapper

To comprehensively test normalization going forward, we should test:

1. Whether an unknown property in the first group of normalization methods is correctly transferred into the normalized object.
2. Whether an unknown property in the second group of normalization methods is correctly NOT transferred into the normalized object.
3. (Not currently implemented) Whether an unknown property in the second group correctly produces some kind of warning object.