add postinstall to init submodules

Author: leoj3n

package.json

@@ -25,6 +25,7 @@
     "genc": "bit-docs -dc",
     "genf": "bit-docs -df",
     "gh-pages": "gh-pages -d gh-pages",
+    "postinstall": "git submodule update --init",
     "pub": "npm run gh-pages",
     "see": "http-server gh-pages",
     "test": "echo \"Error: no test specified\" && exit 1"