Don't use ActiveRecords touch helper as this will reset the taxon_concept's updated_at date. Using a change observer we can just update the dependents_updated_at_column when a dependent object is saved/destroyed
Take the new field into consideration when displaying the taxon concept
[Finishes #49202187] Takes the new field into consideration when rebuilding the taxon_concepts_mview, and when updating the taxon_concepts' touched_at
Added dependents_updated_at to attr_accessible
Check if there's a taxon_concept before trying to update it...
Merge branch 'taxon_concept_descendents_updated_at' into develop