add unique indexes to users

db/migrate/20140516162515_add_unique_indexes_to_users.rb

@@ -0,0 +1,11 @@
+class AddUniqueIndexesToUsers < ActiveRecord::Migration
+  def change
+    remove_index "users", ["email"]
+    add_index "users", ["email"], unique: true
+    remove_index "users", ["login"]
+    add_index "users", ["login"], unique: true
+    remove_index "users", ["authentication_token"]
+    add_index "users", ["authentication_token"], unique: true
+  end
+end
+