React required version (reduxjs#1098)

* Updates references to supported react versions to be > 16.4 per 6.0 release

* Adds missing babel-jest dependency for tests

* Removes outdated test directories for unsupported react versions

Author: joelgallant

CONTRIBUTING.md

@@ -45,7 +45,7 @@ To run in explicit React versions (the number is the version, so `test:16.3` wil
 REACT=16.4 npm run test:ci
 ```
 
-To run tests in all supported React versions, `0.14`, `15`, `16.2`, `16.3`, `16.4`, 16.5`,
+To run tests in all supported React versions, `16.4`, 16.5`,
 ```
 REACT=all npm run test:ci
 ```
@@ -120,11 +120,6 @@ before_install:
   - 'nvm install-latest-npm'
 env:
   matrix:
-  - REACT=0.14
-  - REACT=15
-  - REACT=15.4
-  - REACT=16.2
-  - REACT=16.3
   - REACT=16.4
   - REACT=16.5
 sudo: false

README.md

@@ -11,7 +11,7 @@ Performant and flexible.
 
 ## Installation
 
-React Redux requires **React 0.14 or later.**
+React Redux requires **React 16.4 or later.**
 
 ```
 npm install --save react-redux

package.json

@@ -58,6 +58,7 @@
     "@babel/preset-env": "^7.2.0",
     "babel-core": "^7.0.0-bridge.0",
     "babel-eslint": "^10.0.1",
+    "babel-jest": "^23.6.0",
     "codecov": "^3.1.0",
     "create-react-class": "^15.6.3",
     "cross-env": "^5.2.0",