chore(package): update ember-cli to version 2.12.3

Closes #53

https://greenkeeper.io/

Author: greenkeeper[bot]

package.json

@@ -37,7 +37,7 @@
     "broccoli-asset-rev": "^2.4.2",
     "ember-ajax": "^2.0.1",
     "ember-browserify": "^1.1.9",
-    "ember-cli": "2.11.1",
+    "ember-cli": "2.12.3",
     "ember-cli-app-version": "^2.0.0",
     "ember-cli-babel": "^5.1.6",
     "ember-cli-dependency-checker": "^1.2.0",