Update Mobx devDependencies to peerDependencies

[thereis]

Version

Tell us which versions you are using:

• react-native-router-flux@4.0.0-beta.28
• mobx@4.1.0
• mobx-react@5.0.0

Expected behaviour

I was trying to configure and use mobx as my default state management, but I had some problems while configuring it, because the new version of mobx@4.1.0 and mobx-react@5.0.0, only accepts 1 instance.

react-native-router-flux uses and old version for both of them and is configured as devDependencies
inside of package.json.

Actual behaviour

It's crashing the application after importing an observable, printing the following output:

[mobx] There are multiple mobx instances active. This might lead to unexpected results: See https://github.com/mobxjs/mobx/issues/1082 for details.

Steps to reproduce

1. Create a simple react-native project.
2. Install react-native-router-flux: npm install react-native-router-flux
3. Install mobx and mobx-react with the latest version: npm install mobx mobx-react
4. Create a simple observable object and import it in App.js or even in index.js
5. It's expected to output the following error [mobx] There are multiple mobx instances active. This might lead to unexpected results: See https://github.com/mobxjs/mobx/issues/1082 for details..

Steps to fix

There is a topic created by the developer of Mobx, explaining how to fix this issue for "library developers", mobx issue #1082.

My workaround to fix this problem, was adding the property resolutions to my package.json and use yarn as package manager. This is my package.json

{
  "name": "reactnativetestapp",
  "version": "0.0.1",
  "private": true,
  "scripts": {
    "start": "node node_modules/react-native/local-cli/cli.js start",
    "test": "jest"
  },
  "dependencies": {
    "mobx": "^4.1.0",
    "mobx-react": "^5.0.0",
    "react": "16.3.0-alpha.1",
    "react-native": "0.54.2",
    "react-native-elements": "^0.19.0",
    "react-native-router-flux": "^4.0.0-beta.28",
    "react-native-vector-icons": "^4.5.0"
  },
  "devDependencies": {
    "mobx": "^4.1.0",
    "mobx-react": "^5.0.0",
    "babel-jest": "23.0.0-alpha.0",
    "babel-plugin-module-resolver": "^3.1.0",
    "babel-plugin-transform-decorators-legacy": "^1.3.4",
    "babel-preset-react-native": "4.0.0",
    "jest": "22.4.2",
    "react-test-renderer": "16.3.0-alpha.1"
  },
  "resolutions": {
    "mobx": "^4.1.0",
    "mobx-react": "^5.0.0"
  },
  "jest": {
    "preset": "react-native"
  }
}

Then, I just run yarn install and react-native run-android.

[aksonov]

Closing it now because beta.40 doesn't use mobx