Implement Support for Redux 4 (#206)

* Upgrade to Redux version 4
* Add generate-lockfile script
* Release version 5.1.0

.github/CONTRIBUTING.md

@@ -1,10 +1,12 @@
 # Contributing
 
-[![Dependency Status](https://david-dm.org/pburtchaell/redux-promise-middleware.svg)](https://david-dm.org/pburtchaell/redux-promise-middleware) [![Build Status](https://travis-ci.org/pburtchaell/redux-promise-middleware.svg)](https://travis-ci.org/pburtchaell/redux-promise-middleware) [![Coverage Status](https://coveralls.io/repos/pburtchaell/redux-promise-middleware/badge.svg?branch=master&service=github)](https://coveralls.io/github/pburtchaell/redux-promise-middleware?branch=master)
+[![Dependency Status](https://david-dm.org/pburtchaell/redux-promise-middleware.svg)](https://david-dm.org/pburtchaell/redux-promise-middleware)
+[![Build Status](https://travis-ci.org/pburtchaell/redux-promise-middleware.svg)](https://travis-ci.org/pburtchaell/redux-promise-middleware)
+[![Coverage Status](https://coveralls.io/repos/pburtchaell/redux-promise-middleware/badge.svg?branch=master&service=github)](https://coveralls.io/github/pburtchaell/redux-promise-middleware?branch=master)
 
 **It is imperative that pull requests include tests and documentation and issues follow guidelines.**
 
-Please be familar with the [GitHub Community Guidelines](https://help.github.com/articles/github-community-guidelines/) before contributing to this project. If you are new to open source, check out this 38 minute course on [how to contribute to open source on GitHub](https://egghead.io/courses/how-to-contribute-to-an-open-source-project-on-github). It's free! :smile:
+Please be familiar with the [GitHub Community Guidelines](https://help.github.com/articles/github-community-guidelines/) before contributing to this project. If you are new to open source, check out this 38 minute course on [how to contribute to open source on GitHub](https://egghead.io/courses/how-to-contribute-to-an-open-source-project-on-github). It's free! :smile:
 
 ## Getting Started
 
@@ -22,7 +24,35 @@ It's okay to ask for help via a GitHub issue, but first read the ["Filing an Iss
 * Can I reduce the code example to the bare minimum required to explain what I need help with?
 * Can I create a [JSBin](https://jsbin.com/?html,output) for the code example?
 * Can I explain what the expected behavior is?
-* Can I explain what the actual beavior is?
+* Can I explain what the actual behavior is?
+
+## Upgrading Dependencies
+
+Use Yarn instead of npm to upgrade dependencies.
+
+You can interactively upgrade dependencies:
+
+```
+yarn upgrade-intractive
+```
+
+Or you can upgrade dependencies one by one. For example, to upgrade Redux, you would run a command like this:
+
+```
+yarn add [email protected] -D
+```
+
+Install [synp](https://github.com/imsnif/synp):
+
+```
+npm install -g synp
+```
+
+Sync package-lock.json with yark.lock by running:
+
+```
+yarn generate-lockfile
+```
 
 ## Found a Bug?