Drop Organization from database

Rolling back this feature. It was a nice attempt but no one ever followed up
and made this something else than a code of conduct holder...

db/migrate/20181229233813_add_code_of_conduct_to_conference.rb

@@ -0,0 +1,5 @@
+class AddCodeOfConductToConference < ActiveRecord::Migration[7.0]
+  def change
+    add_column :conferences, :code_of_conduct, :text
+  end
+end