ci(node): drop node v4 and v5

Author: chimurai

.travis.yml

@@ -6,11 +6,6 @@ node_js:
 - '8'
 - '7'
 - '6'
-- '5'
-- '4'
-before_install:
-# https://github.com/npm/npm/issues/11283
-- npm set progress=false
 after_success: npm run coveralls
 env:
   global:

package.json

@@ -65,7 +65,7 @@
     "micromatch": "^3.1.10"
   },
   "engines": {
-    "node": ">=4.0.0"
+    "node": ">=6.0.0"
   },
   "husky": {
     "hooks": {