upgrade to node 4.2.1

services/docstore/.nvmrc

@@ -0,0 +1 @@
+4.2.1

services/docstore/package.json

@@ -9,7 +9,7 @@
   },
   "dependencies": {
     "settings-sharelatex": "git+https://github.com/sharelatex/settings-sharelatex.git#v1.0.0",
-    "logger-sharelatex": "git+https://github.com/sharelatex/logger-sharelatex.git#v1.0.0",
+    "logger-sharelatex": "git+https://github.com/sharelatex/logger-sharelatex.git#v1.4.0",
     "metrics-sharelatex": "git+https://github.com/sharelatex/metrics-sharelatex.git#v1.1.0",
     "mongojs": "0.18.2",
     "express": "~4.1.1",
@@ -31,5 +31,8 @@
     "chai": "~1.9.1",
     "grunt-forever": "~0.4.4",
     "request": "~2.34.0"
+  },
+  "engines": {
+    "node": "~4.2.1"
   }
 }