chore(package): update steal to version 2.1.5

Closes #284

Author: greenkeeper[bot]

package.json

@@ -73,7 +73,7 @@
     "detect-cyclic-packages": "^1.1.0",
     "done-serve": "^2.0.0",
     "jshint": "^2.9.1",
-    "steal": "^1.0.0",
+    "steal": "^2.1.5",
     "steal-qunit": "^1.0.0",
     "steal-tools": "^1.0.1",
     "testee": "^0.8.0"