chore(README.md/package.json): typo + lock down devDependencies

- README.md: Corrected code for delete button
- package.json: lock devDependencies to specific version

README.md

@@ -318,7 +318,7 @@ export default class FileListener extends Component {
                            <Thumbnail id={ id } uploader={ uploader } />
                            <DeleteButton id={ id } uploader={ uploader } />
                         </div>
-                    ))
+                    })
                 }
             </div>
         )

package.json

@@ -30,37 +30,37 @@
     "object-assign": "4.1.1"
   },
   "devDependencies": {
-    "babel-cli": "latest",
-    "babel-core": "latest",
-    "babel-eslint": "latest",
-    "babel-loader": "latest",
-    "babel-plugin-rewire": "latest",
-    "babel-preset-es2015": "latest",
-    "babel-preset-react": "latest",
-    "babel-plugin-syntax-class-properties": "latest",
-    "babel-plugin-transform-class-properties": "latest",
-    "babel-plugin-transform-object-rest-spread": "latest",
-    "css-loader": "latest",
-    "es6-promise": "latest",
-    "eslint": "latest",
-    "eslint-plugin-react": "latest",
-    "extract-text-webpack-plugin": "latest",
-    "jasmine": "latest",
-    "jasmine-core": "latest",
-    "karma": "latest",
-    "karma-firefox-launcher": "latest",
-    "karma-jasmine": "latest",
-    "karma-sauce-launcher": "latest",
-    "karma-sourcemap-loader": "latest",
-    "karma-spec-reporter": "latest",
-    "karma-webpack": "latest",
-    "react": "latest",
-    "react-addons-css-transition-group": "latest",
-    "react-addons-test-utils": "latest",
-    "react-dom": "latest",
-    "style-loader": "latest",
+    "babel-cli": "6.23.0",
+    "babel-core": "6.23.1",
+    "babel-eslint": "7.1.1",
+    "babel-loader": "6.3.2",
+    "babel-plugin-rewire": "1.0.0",
+    "babel-preset-es2015": "6.22.0",
+    "babel-preset-react": "6.23.0",
+    "babel-plugin-syntax-class-properties": "6.13.0",
+    "babel-plugin-transform-class-properties": "6.23.0",
+    "babel-plugin-transform-object-rest-spread": "6.23.0",
+    "css-loader": "0.26.2",
+    "es6-promise": "4.0.5",
+    "eslint": "3.16.1",
+    "eslint-plugin-react": "6.10.0",
+    "extract-text-webpack-plugin": "1.0.1",
+    "jasmine": "2.5.3",
+    "jasmine-core": "2.5.2",
+    "karma": "1.5.0",
+    "karma-firefox-launcher": "1.0.0",
+    "karma-jasmine": "1.1.0",
+    "karma-sauce-launcher": "1.1.0",
+    "karma-sourcemap-loader": "0.3.7",
+    "karma-spec-reporter": "0.0.30",
+    "karma-webpack": "2.0.2",
+    "react": "15.4.2",
+    "react-addons-css-transition-group": "15.4.2",
+    "react-addons-test-utils": "15.4.2",
+    "react-dom": "15.4.2",
+    "style-loader": "0.13.2",
     "webpack": "1.14.0",
-    "webpack-node-externals": "latest"
+    "webpack-node-externals": "1.5.4"
   },
   "engines": {
     "node": ">=5.0.0"