Bump dependencies to be Node 8 compatible

package.json

@@ -49,10 +49,10 @@
     "eslint-plugin-import": "^1.8.1",
     "eslint-plugin-jsx-a11y": "^1.5.3",
     "eslint-plugin-react": "^5.2.2",
-    "gulp": "~3.8.11",
+    "gulp": "^3.9.1",
     "gulp-autoprefixer": "~3.0.2",
     "gulp-rename": "^1.2.2",
-    "gulp-sass": "~2.3.1",
+    "gulp-sass": "3.1.0",
     "gulp-sourcemaps": "~1.5.2",
     "gulp-util": "~2.2.14",
     "jest": "^20.0.4",