Fix API requests to localhost on Android

[isaiahgrey93]

Finally was able to resolve an issue I've dealt with in several apps where on the Android platform, requests to localhost do not resolve despite adb reverse being called correctly.
I was able to fix this issue by modify the environment variable while in dev mode (_DEV_ = true) by pointing at 10.0.2.2 instead of localhost :

if (__DEV__ && Platform.OS === 'android') {
  ENV.API_URL = API_URL.replace('localhost', '10.0.2.2');
}

We should add this to our default setup.