Add structured errors to schema

db/migrate/20170703075832_create_error_templates.rb

@@ -0,0 +1,11 @@
+class CreateErrorTemplates < ActiveRecord::Migration
+  def change
+    create_table :error_templates do |t|
+      t.belongs_to :execution_environment
+      t.string :name
+      t.string :signature
+
+      t.timestamps null: false
+    end
+  end
+end