chore(package): update ember-cli-babel to version 7.20.1

Closes #56

Author: greenkeeper[bot]

package.json

@@ -78,7 +78,7 @@
     "ember-ajax": "^2.4.1",
     "ember-cli": "2.10.0",
     "ember-cli-app-version": "^2.0.0",
-    "ember-cli-babel": "^5.1.7",
+    "ember-cli-babel": "^7.20.1",
     "ember-cli-dependency-checker": "^1.3.0",
     "ember-cli-eslint": "3.0.0",
     "ember-cli-htmlbars": "^1.0.10",