[Storybook-Native] undefined is not an object (evaluating '_expo.KeepAwake.activate')

## Description

While running storybook-native `undefined is not an object (evaluating '_expo.KeepAwake.activate')` issue appears

## Expected Behavior

`bluebase storybook-native:start` should run successfully.

## Actual Behavior


## Possible Fix

This issue is created due to storybook-native AppEntry.js its content should be,

```
import App from './../../bluebase/storybook-native/storybook';
import { activateKeepAwake } from 'expo-keep-awake';
import { registerRootComponent } from 'expo';

if (__DEV__) {
activateKeepAwake();
}

registerRootComponent(App);
```

## Steps to Reproduce

1. create a plugin
2. `bluebase storybook-native:init`
3. `bluebase storybook-native:start`

## Context

## Screenshots

## Your Environment

* Version used: `0.0.16`
* Environment name and version (e.g. Chrome 39, node.js 5.4): node.js 10.16.3
* Operating System and version (desktop or mobile): Ubuntu 18

Start with the Storybook-Native AppEntry.js mentioned in the issue and inspect the KeepAwake import and activation call. Reproduce the problem with bluebase storybook-native:init followed by bluebase storybook-native:start; done means the command runs successfully without the undefined KeepAwake error.

由索引模型根据 Issue 内容生成。