Add tax_references, its controller and some basic pages for viewing ref data about taxes.

db/migrate/20200909112404_create_tax_references.rb

@@ -0,0 +1,13 @@
+class CreateTaxReferences < ActiveRecord::Migration[6.0]
+  def change
+    create_table :tax_references do |t|
+      t.integer :year
+      t.float :hourly_wage
+      t.integer :min_monthly_hours
+      t.float :worker_percentage
+      t.float :employer_percentage
+
+      t.timestamps
+    end
+  end
+end