chore(package): update steal to version 2.2.3

Closes #68

Author: greenkeeper[bot]

package.json

@@ -35,7 +35,7 @@
     "glob": "^7.1.1",
     "jshint": "^2.9.1",
     "qunit-composite": "^2.0.0",
-    "steal": "^1.12.6",
+    "steal": "^2.2.3",
     "steal-css": "^1.3.2",
     "steal-qunit": "^1.0.2",
     "testdouble": "^3.0.0",