Add spec for git-contest-list sites
user
```ruby
require 'spec_helper'

describe "T012: git-contest-list" do
  before do
    ENV['GIT_CONTEST_CONFIG'] = "#{@temp_dir}/config.yml"
  end

  context "git-contest-list sites" do
    before do
      # create config
      File.open "#{@temp_dir}/config.yml", 'w' do |file|
        file.write <<EOF
sites:
  test_site1:
    driver: test_driver1
    user: test_user1
    password: test_password1
  test_site2:
    driver: test_driver2
    user: test_user2
    password: test_password2
  test_site3:
    driver: test_driver3
    user: test_user3
    password: test_password3
EOF
      end
    end

    it "should include site name" do
      ret = bin_exec "list sites"
      (1..3).each {|x| expect(ret).to include "test_site#{x}" }
    end

    it "should include user name" do
      ret = bin_exec "list sites"
      (1..3).each {|x| expect(ret).to include "test_user#{x}" }
    end

    it "should include driver name" do
      ret = bin_exec "list sites"
      (1..3).each {|x| expect(ret).to include "test_driver#{x}" }
    end

    it "should NOT include password" do
      ret = bin_exec "list sites"
      (1..3).each {|x| expect(ret).not_to include "test_password#{x}" }
    end
  end

end
```
assistant