Avoid NPM when starting Dockerfile

Dockerfile

@@ -22,4 +22,4 @@ COPY . ${WORK}
 RUN npm test
 
 # start service
-CMD [ "npm", "start" ]
+CMD [ "./bin/start" ]

bin/start

@@ -0,0 +1,2 @@
+#!/bin/bash
+exec node index.js

package.json

@@ -12,7 +12,7 @@
     "coverage": "node_modules/.bin/istanbul cover test/unit/run.js",
     "docs": "./bin/generate-docs",
     "lint": "jshint .",
-    "start": "node index.js",
+    "start": "./bin/start",
     "test": "npm run unit",
     "travis": "npm run check-dependencies && npm test",
     "unit": "./bin/units",