Bump spring from 1.4.0 to 2.0.2

Bumps [spring](https://github.com/rails/spring) from 1.4.0 to 2.0.2.
- [Changelog](https://github.com/rails/spring/blob/master/CHANGELOG.md)
- [Commits](rails/spring@v1.4.0...v2.0.2)

Gemfile.lock

@@ -368,7 +368,8 @@ GEM
     slop (3.6.0)
     spoon (0.0.4)
       ffi
-    spring (1.4.0)
+    spring (2.0.2)
+      activesupport (>= 4.2)
     sprockets (3.7.2)
       concurrent-ruby (~> 1.0)
       rack (> 1, < 3)