Enable Greenkeeper support about re-start

[piranna]

Totally agree with this :-D

[piranna]

 autoprefixer                          ^6.7.2  →       ^7.1.1 
 babel-loader                         ^6.2.10  →       ^7.1.1 
 babel-preset-react-app                ^2.2.0  →       ^3.0.1 
 case-sensitive-paths-webpack-plugin   ^1.1.4  →       ^2.1.1 
 chalk                                 ^1.1.3  →       ^2.0.1 
 cross-spawn                           ^4.0.2  →       ^5.1.0 
 css-loader                           ^0.26.1  →      ^0.28.4 
 dotenv                                ^2.0.0  →       ^4.0.0 
 eslint                               ^3.16.1  →       ^4.1.1 
 eslint-config-react-app               ^0.6.2  →       ^1.0.5 
 eslint-plugin-jsx-a11y                ^4.0.0  →       ^6.0.2 
 eslint-plugin-react                   ^6.4.1  →       ^7.1.0 
 extract-text-webpack-plugin           ^1.0.1  →       ^2.1.2 
 file-loader                          ^0.10.0  →      ^0.11.2 
 fs-extra                             ^0.30.0  →       ^3.0.1 
 postcss-loader                        ^1.2.2  →       ^2.0.6 
 prettier                              0.22.0  →        1.5.2 
 promise                               ^7.1.1  →       ^8.0.0 
 react-dev-utils                       ^0.5.2  →       ^3.0.2 
 react-dom                             15.5.4  →       15.6.1 
 react-native-web                      0.0.88  →      0.0.108 
 react-native-windows                  0.42.0  →  0.46.0-rc.0 
 react-router                           4.0.0  →        4.1.1 
 react-router-dom                       4.0.0  →        4.1.1 
 react-router-native                    4.0.0  →        4.1.1 
 style-loader                         ^0.13.1  →      ^0.18.2 
 webpack                              ^1.14.0  →       ^3.0.0 
 webpack-dev-server                   ^1.16.2  →       ^2.5.0 

That's A LOT of outdated dependencies that would need to be upgraded... @Greenkeeper and having unit tests would fix them.