Get audio recording working on Android

Development of the app so far has used the iOS emulator for testing. We need to run the app on an Android emulator to ensure that it builds/runs properly and has feature parity with the iOS app.

To do

- [x] Setup local machine to run app on Android emulator. See ["Building projects with native code"](https://facebook.github.io/react-native/docs/getting-started.html)
- [x] Debug and resolve any issues
- [ ] Address the fact that [Android does not support recording in the PCM format](https://developer.android.com/reference/android/media/MediaRecorder.AudioEncoder) that is [needed to send to AWS Lex](https://github.com/jsierles/react-native-audio/issues/213#issuecomment-411980566)