add rake task for rebuild index

lib/tasks/index.rake

@@ -0,0 +1,11 @@
+# encoding: utf-8 
+
+namespace :index do
+  task :rebuild => :environment do
+    Sunspot.remove_all!
+    Sunspot.commit
+    Sunspot.index NewsBulletin.all
+    Sunspot.index Bulletin.all
+    Sunspot.commit
+  end
+end