Add pluralization irregularity for taxon -> taxa
Add IcznGroup model and seed initial data
Add Taxon model, with relationships to iczn_group and import_job
Add OTU resource
Add parent/children relationships on taxon

Added a taxon_ancestors model, and this thread on SO was helpful:

http://stackoverflow.com/questions/6069921/has-many-children-and-has-man
y-parents
Fix improper use of has_many
Implemented saving to model in import job

Not yet working
Correct where on import

.where is not valid on a single object, so using it on children

Import now creates Taxon and OTU objects, linked to the ImportJob model that created them.
There's no UI for browsing the taxa yet, but there are controller stubs from generating
the resources