Upgrades Ember CLI to 2.13

Ember CLI 2.13 uses Yarn internally if there’s a lock file present,
which is useful for `ember install` and family.

Author: locks

package.json

@@ -25,7 +25,7 @@
     "bower": "1.8.0",
     "broccoli-asset-rev": "2.5.0",
     "ember-ajax": "^3.0.0",
-    "ember-cli": "2.12.0",
+    "ember-cli": "^2.13.2",
     "ember-cli-app-version": "^3.0.0",
     "ember-cli-babel": "5.2.4",
     "ember-cli-dependency-checker": "^2.0.0",