use factory_girl instead fixture for rspec test

1. Install factory_girl
  sudo gem install thoughtbot-factory_girl --source="http://gems.github.com"

2. Configure
   create factory.rb file in spec directory, i.e.
   Factory.define :user do |u|
    u.login "testing"
    u.password "testing"
   end

   in spec_helper file add:
   require 'factory_girl'
   require File.expand_path(File.dirname(__FILE__) + /factory)

3. Use factory_girl
   Factory(:user), Factory.build(:user)