Add route and controller for incoming messages

app/controllers/messages_controller.rb

@@ -0,0 +1,25 @@
+class MessagesController < ApplicationController
+  allow_unauthenticated_access
+  skip_before_action :verify_authenticity_token
+
+  def create
+    skip_authorization
+
+    @message_params = message_params
+    @contest = Contest.find_by_token_for(:token, params[:token])
+    @message = Message.new(text: params[:text], time_seconds: params[:time_seconds], contest: @contest)
+    if @contest && @message.save
+      respond_to do |format|
+        format.json  { render json: {}, status: 200 }
+      end
+    else
+      respond_to do |format|
+        format.json  { render json: { error: "invalid contest token" }, status: 400 }
+      end
+    end
+  end
+
+  def message_params
+    params.expect(message: [ :text, :time_seconds, :token ])
+  end
+end