Release version that supports 4.0 and above

[technicalpickles]

I wanted to give this a try, but I'm getting this from bundler:

Bundler could not find compatible versions for gem "spring":
  In snapshot (Gemfile.lock):
    spring (>= 3.0.0)

  In Gemfile:
    spring

    spring-commands-rspec was resolved to 1.0.4, which depends on
      spring (>= 0.9.1)

    spring-watcher-listen was resolved to 2.0.0, which depends on
      spring (~> 1.2)

It looks like #26 addresses this, so could we get a release with it?

[pjg]

This issue should now read "Release version that supports spring v4.0".

[kroehre]

What's blocking this? @rafaelfranca