don't allow an object to be a synonym of itself

[brettatoms]

Shouldn't allow a Family, Genus, Species to be a synonym of themselves. We could set this up on the mapper so that if a synonyms is commited where synonym.synonym_id==synonym.species_id it raises an error.

Could also just make sure its not possible in the editor by not putting the synonyms in the completions list.

Or we could do both.