fix(package): update ember-cli-babel to version 7.4.2

Closes #78

Author: greenkeeper[bot]

package.json

@@ -30,7 +30,7 @@
     "broccoli-funnel": "^2.0.1",
     "broccoli-merge-trees": "^3.0.1",
     "broccoli-stew": "^2.0.0",
-    "ember-cli-babel": "^6.16.0",
+    "ember-cli-babel": "^7.4.2",
     "ember-get-config": "^0.2.4",
     "hammer-timejs": "^1.1.0"
   },