Bump dependencies; drop support for Node <4

.travis.yml

@@ -1,8 +1,6 @@
 language: node_js
 matrix:
   include:
-    - node_js: '0.12'
-    - node_js: iojs
     - node_js: 4
     - node_js: 6
     - node_js: node

package.json

@@ -6,7 +6,7 @@
   "jsnext:main": "src/index.js",
   "author": "Tim De Pauw <hi@tmdpw.eu> (https://tmdpw.eu/)",
   "engines": {
-    "node": ">=0.12.0"
+    "node": ">=4"
   },
   "license": "MIT",
   "files": [
@@ -31,31 +31,29 @@
     "resolve": "^1.1.7"
   },
   "devDependencies": {
-    "babel-eslint": "^6.1.0",
-    "babel-preset-es2015": "^6.9.0",
-    "babel-register": "^6.9.0",
+    "babel-preset-es2015": "^6.16.0",
+    "babel-register": "^6.16.3",
     "chai": "^3.5.0",
-    "chai-as-promised": "^5.3.0",
+    "chai-as-promised": "^6.0.0",
     "del": "^2.2.1",
     "gulp": "^3.9.1",
     "gulp-babel": "^6.1.2",
     "gulp-coveralls": "^0.1.4",
     "gulp-if": "^2.0.1",
     "gulp-istanbul": "^1.0.0",
-    "gulp-load-plugins": "^1.2.4",
+    "gulp-load-plugins": "^1.3.0",
     "gulp-mocha": "^3.0.0",
     "gulp-notify": "^2.2.0",
     "gulp-plumber": "^1.1.0",
     "gulp-sourcemaps": "^1.6.0",
-    "gulp-standard": "^7.0.1",
+    "gulp-standard": "^8.0.2",
     "in-publish": "^2.0.0",
     "isparta": "^4.0.0",
     "run-sequence": "^1.2.2",
-    "sinon": "^1.17.4",
+    "sinon": "^1.17.6",
     "sinon-chai": "^2.8.0"
   },
   "standard": {
-    "parser": "babel-eslint",
     "globals": [
       "describe",
       "it",