fix(package): update ember-cli-babel to version 7.2.0

Closes #284

Author: greenkeeper[bot]

package.json

@@ -39,7 +39,7 @@
     "ember-addon"
   ],
   "dependencies": {
-    "ember-cli-babel": "^6.6.1",
+    "ember-cli-babel": "^7.2.0",
     "ember-cli-htmlbars": "^2.0.1",
     "ember-cli-htmlbars-inline-precompile": "^1.0.0",
     "ember-cli-sass": "7.2.0",