use 'rails runner' when rails4

When I use rails4, 'bin/rails runner' returns an error.

```
# confirm rails version
$ bundle exec rails r 'puts Rails.version'
4.0.1
```

```
# run bin/rails
/bin/bash -l -c 'which gem ; which ruby; gem list | grep chronic; cd /home/user_name/rails_app_name && bundle list | grep chronic && bundle show chronic && bundle exec bin/rails runner -e development '\''puts 1'\'''

# result
/usr/local/rbenv/shims/gem
/usr/local/rbenv/shims/ruby
3:chronic (0.10.2)
19:  * chronic (0.10.2)
/home/user_name/rails_app_name/vendor/bundle/ruby/2.0.0/gems/chronic-0.10.2
Could not find chronic-0.10.2 in any of the sources
Run `bundle install` to install missing gems.
```

```
# run rails
/bin/bash -l -c 'which gem ; which ruby; gem list | grep chronic; cd /home/user_name/rails_app_name && bundle list | grep chronic && bundle show chronic && bundle exec rails runner -e development '\''puts 1'\'''

# result
/usr/local/rbenv/shims/gem
/usr/local/rbenv/shims/ruby
3:chronic (0.10.2)
19:  * chronic (0.10.2)
/home/user_name/rails_app_name/vendor/bundle/ruby/2.0.0/gems/chronic-0.10.2
1
```