Add web app model, service to fetch metadata

app/models/app_catalog/web_app.rb

@@ -0,0 +1,9 @@
+class AppCatalog::WebApp < ApplicationRecord
+
+  store :metadata, coder: JSON
+
+  validates :url, presence: true, uniqueness: true
+  validates :url, format: { with: URI.regexp },
+                  if: Proc.new { |a| a.url.present? }
+
+end