add message model and migration

test/fixtures/messages.yml

@@ -0,0 +1,11 @@
+# Read about fixtures at https://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html
+
+# This model initially had no columns defined. If you add columns to the
+# model remove the '{}' from the fixture names and add the columns immediately
+# below each fixture, per the syntax in the comments below
+#
+one: {}
+# column: value
+#
+two: {}
+# column: value

test/models/message_test.rb

@@ -0,0 +1,7 @@
+require 'test_helper'
+
+class MessageTest < ActiveSupport::TestCase
+  # test "the truth" do
+  #   assert true
+  # end
+end