move newrelic + deploytags gem to production env, rename cap tasks to .rake

lib/capistrano/tasks/web.rake

@@ -0,0 +1,24 @@
+namespace :web do
+  desc "Present a maintenance page to visitors."
+  task :disable do
+    on roles(:app) do
+      maintenance_html_path = "#{current_path}/public/maintenance.html.bak"
+      if test("[ -e #{maintenance_html_path} ]")
+        execute :mv, maintenance_html_path, "#{current_path}/public/maintenance.html"
+      end
+    end
+  end
+
+  desc "Makes the application web-accessible again."
+  task :enable do
+    on roles(:app) do
+      maintenance_html_path = "#{current_path}/public/maintenance.html"
+      if test("[ -e #{maintenance_html_path} ]")
+        execute :mv, maintenance_html_path, "#{current_path}/public/maintenance.html.bak"
+      end
+    end
+  end
+end
+
+before "deploy:started", "web:disable"
+after "deploy:published", "web:enable"