Remove patternengine-node-mustache as a dependency in core

closes #617

Author: bmuenzenmeyer

package.json

@@ -16,7 +16,6 @@
     "lodash": "~4.13.1",
     "markdown-it": "^6.0.1",
     "node-fetch": "^1.6.0",
-    "patternengine-node-mustache": "^1.0.0",
     "graphlib": "^2.1.1"
   },
   "devDependencies": {