Babel 7: Update babel devDependencies to stable version + drop nodejs 4 (#93)

* chore: update babel to stable version

* ci: drop nodejs 4 support

* ci: add nodejs 10 support

* chore: update minimum nodejs requirement in package.json

* docs: update README.md

Author: sibiraj-s

.travis.yml

@@ -1,6 +1,6 @@
 sudo: false
 language: node_js
 node_js:
+  - '10'
   - '8'
   - '6'
-  - '4'

README.md

@@ -7,42 +7,38 @@
 
 *Issues with the output should be reported on the Babel [issue tracker](https://github.com/babel/babel/issues).*
 
-
 ## Install
 
 ```
 $ yarn add --dev grunt-babel @babel/core @babel/preset-env
 ```
 
-
 ## Usage
 
 ```js
 require('load-grunt-tasks')(grunt); // npm install --save-dev load-grunt-tasks
 
 grunt.initConfig({
-	babel: {
-		options: {
-			sourceMap: true,
-			presets: ['@babel/preset-env']
-		},
-		dist: {
-			files: {
-				'dist/app.js': 'src/app.js'
-			}
-		}
-	}
+  babel: {
+    options: {
+      sourceMap: true,
+      presets: ['@babel/preset-env']
+    },
+    dist: {
+      files: {
+        'dist/app.js': 'src/app.js'
+      }
+    }
+  }
 });
 
 grunt.registerTask('default', ['babel']);
 ```
 
-
 ## Options
 
 See the Babel [options](https://babeljs.io/docs/usage/options), except for `filename` which is handled for you.
 
-
 ## License
 
 MIT © [Sindre Sorhus](https://sindresorhus.com)

package.json

@@ -10,7 +10,7 @@
     "url": "sindresorhus.com"
   },
   "engines": {
-    "node": ">=4"
+    "node": ">=6"
   },
   "scripts": {
     "lint": "eslint .",
@@ -34,12 +34,12 @@
     "compiler"
   ],
   "peerDependencies": {
-    "@babel/core": "^7.0.0-0",
+    "@babel/core": "^7.0.0",
     "grunt": ">=0.4.0"
   },
   "devDependencies": {
-    "@babel/core": "^7.0.0-beta.42",
-    "@babel/preset-env": "^7.0.0-beta.42",
+    "@babel/core": "^7.0.0",
+    "@babel/preset-env": "^7.0.0",
     "babel-eslint": "^8.0.0",
     "eslint": "^4.19.0",
     "eslint-config-babel": "^7.0.2",