jonleighton/spring — pull request #135 by kylewelsby (2013-05-02 11:15:30+00:00)
Title: Make ListenWatcher optional closes #128

By default spring is configured to watch_via [`listen`](https://github.com/guard/listen) is available spring will use that, alternatively spring can be configured to use `:listen`, `:polling`, or a`CustomClass`.

```ruby
Spring.watch_via = :polling
```