create remote evaluation

db/migrate/20170202170437_create_remote_evaluation_mappings.rb

@@ -0,0 +1,11 @@
+class CreateRemoteEvaluationMappings < ActiveRecord::Migration
+  def change
+    create_table :remote_evaluation_mappings do |t|
+      t.integer   "user_id",          null: false
+      t.integer   "exercise_id",      null: false
+      t.string    "validation_token",  null: false
+      t.datetime  "created_at"
+      t.datetime  "updated_at"
+    end
+  end
+end