Use PostCSS 6.0 and drop node 0.12

Author: w0rm

.travis.yml

@@ -4,4 +4,3 @@ node_js:
   - stable
   - 6
   - 4
-  - 0.12

package.json

@@ -4,7 +4,7 @@
   "description": "PostCSS gulp plugin",
   "main": "index.js",
   "scripts": {
-    "pretest": "node-version-gte-4 && eslint index.js || echo \"ESLint not supported\"",
+    "pretest": "eslint index.js",
     "test": "mocha test.js"
   },
   "repository": {
@@ -25,15 +25,14 @@
   "homepage": "https://github.com/postcss/gulp-postcss",
   "dependencies": {
     "gulp-util": "^3.0.8",
-    "postcss": "^5.2.12",
+    "postcss": "^6.0.0",
     "postcss-load-config": "^1.2.0",
     "vinyl-sourcemaps-apply": "^0.2.1"
   },
   "devDependencies": {
     "eslint": "^3.19.0",
     "gulp-sourcemaps": "^2.6.0",
     "mocha": "^3.3.0",
-    "node-version-check": "^2.1.1",
     "proxyquire": "^1.7.11",
     "sinon": "^2.2.0"
   },