chore(package): update ember-data to version 3.15.0

Closes #10

Author: greenkeeper[bot]

package.json

@@ -43,7 +43,7 @@
     "ember-cli-sri": "^2.1.0",
     "ember-cli-test-loader": "^2.2.0",
     "ember-cli-uglify": "^2.0.0",
-    "ember-data": "^2.11.0",
+    "ember-data": "^3.15.0",
     "ember-disable-proxy-controllers": "^1.0.1",
     "ember-export-application-global": "^2.0.0",
     "ember-font-awesome": "3.1.1",