Add has_and_belongs_to_many relationship from Taxon to TraitGroups
Forgot to add migration
Add some stuff to trait_group for taxa
Update IcznGroup for levels

Add additional levels to seeds and level parameter
Add dependent => nullify to display_fomat
Reworking Otu <-> Taxon relationships to not enforce a predefined taxonomy

Removed group-specific taxon foreign keys from Otu
Added has_and_belongs_to_many taxa relationship on Otu
Added utilities to help navigate OTUs by IcznGroup name
Removed scopes for species/family/order/etc from Taxon and cleaned up
dead code
Use new Otu <-> Taxon relationships in import_job

Remove magic words (e.g. 'species', 'order' )
Add Taxon.descendants_with_level and under_iczn_group

descendants_with_level dynamically generates SQL joins across the
TaxonAncestors table
Refactoring search controller to remove specific IcznGroup levels
WIP on rebuilding search form to remove hard-coded levels.
Fix bug in taxa_in_iczn_group_with_parents

Was flattening to get ALL taxa at this level.  Instead want
intersection, so that filter is applied correctly.
Finished rebuilding javascript for search form
Update search_controller and results to take advantage of iczn groups

Removed hard-coded values of 'htg', 'order', etc.
comment about getting rid of stuff
WIP on updating search form markup

Moved selects inside of TDs.  Javascript will need to be updated as
they are not siblings anymore
Fixed sibling usage on taxa
Fixed sibling usage on traits
Re-enable --All-- Selections in taxonomy
Tidy up select boxes for traits
Remove --All-- option from highest taxon level