Fix load test taxa

Hey @kueda, I ended up doing some yak shaving and fixing the issues with taxon_spec being run with other specs. I also made it so the Flickr tests won't fail for developers (like myself) who haven't set a valid API key.

The main issue with load_test_taxa was that it was creating duplicate taxa. This was only happening under certain circumstances when load_test_taxa was run more than once.