Update dev dependencies

- Also added npm-check-updates to the dev dependencies.

package.json

@@ -32,34 +32,36 @@
   "license": "MIT",
   "devDependencies": {
     "babel-plugin-add-module-exports": "^0.2.1",
-    "babel-plugin-transform-es2015-modules-umd": "^6.12.0",
-    "babel-preset-es2015": "^6.16.0",
-    "eslint": "^3.9.1",
-    "eslint-config-airbnb-base": "^10.0.1",
+    "babel-plugin-transform-es2015-modules-umd": "^6.23.0",
+    "babel-preset-es2015": "^6.22.0",
+    "eslint": "^3.17.1",
+    "eslint-config-airbnb-base": "^11.1.1",
     "eslint-config-es5": "^0.5.0",
     "eslint-plugin-import": "^2.2.0",
     "gulp": "^3.9.1",
     "gulp-add-src": "^0.2.0",
     "gulp-autoprefixer": "^3.1.1",
     "gulp-babel": "^6.1.2",
-    "gulp-bump": "^2.4.0",
+    "gulp-bump": "^2.7.0",
     "gulp-eslint": "^3.0.1",
-    "gulp-filter": "^4.0.0",
-    "gulp-git": "^1.12.0",
+    "gulp-filter": "^5.0.0",
+    "gulp-git": "^2.0.1",
     "gulp-help": "^1.6.1",
-    "gulp-if": "^2.0.1",
+    "gulp-if": "^2.0.2",
     "gulp-rename": "^1.2.2",
-    "gulp-sass": "^2.3.2",
-    "gulp-sass-lint": "^1.2.0",
-    "gulp-sourcemaps": "^2.2.0",
+    "gulp-sass": "^3.1.0",
+    "gulp-sass-lint": "^1.3.2",
+    "gulp-sourcemaps": "^2.4.1",
     "gulp-tag-version": "^1.3.0",
-    "gulp-uglify": "^2.0.0",
+    "gulp-uglify": "^2.1.0",
     "gulp-uglifycss": "^1.0.6",
-    "merge-stream": "^1.0.0",
-    "yargs": "^6.3.0"
+    "merge-stream": "^1.0.1",
+    "npm-check-updates": "^2.10.3",
+    "yargs": "^7.0.1"
   },
   "scripts": {
     "gulp": "gulp",
+    "update-modules": "npm update --save-dev && npm-check-updates -u",
     "clean": "rimraf ./node_modules"
   }
 }