Update React and Combine Tests

[johnthepink]

This updates react to 15.4.1, and react-native to 0.38.0. React 15.4 fixed the injectEnvironment issue mentioned here, which prevented our tests from using enzyme and react-test-renderer in the same file.

[johnthepink]

Ran in to an interesting issue, any suggestions more than welcome.

Upgrading React introduced an issue on the CI with importing "React" vs "react". See this comment.

Using the jest preset included in react-native actually fixed this issue, but caused tests to fail that were making actual network requests (see server swapi test).

For now, I have downgraded to react 15.4.0. Moving forward, we should see if we can fix the network request tests, as the react-native jest preset included in react-native cleans up a lot of test logs.

[stubailo]

Looks great! Perhaps let's open an issue for the other thing and merge this PR?

[jbaxleyiii]

@johnthepink thanks so much for doing this! It may be worth setting up greenkeeper for this repo. @stubailo is that something someone at MDG could do?

[johnthepink]

@jbaxleyiii @stubailo creating an issue now.