Update ember-cli to 3.18

Author: lukemelia

package.json

@@ -26,7 +26,7 @@
   "devDependencies": {
     "chai": "^3.5.0",
     "chai-as-promised": "^6.0.0",
-    "ember-cli": "^2.12.0",
+    "ember-cli": "^3.18.0",
     "ember-cli-release": "^1.0.0-beta.2",
     "eslint": "^3.18.0",
     "glob": "^7.1.1",