chore(package): update ember-source to version 3.7.0

Closes #20

Author: greenkeeper[bot]

package.json

@@ -52,7 +52,7 @@
     "ember-maybe-import-regenerator": "^0.1.6",
     "ember-qunit": "^3.4.1",
     "ember-resolver": "^5.0.1",
-    "ember-source": "~3.5.1",
+    "ember-source": "~3.7.0",
     "ember-source-channel-url": "^1.1.0",
     "ember-try": "^1.0.0",
     "eslint-plugin-ember": "^5.2.0",