Use "files" field in package.json

Include only files relevant to the end user on npm.

Author: Hadrien Milano

.gitignore

@@ -1,3 +1,2 @@
 node_modules/*
-!node_modules/node-static
-npm-debug.log 
+npm-debug.log

package.json

@@ -16,6 +16,10 @@
     "pretest": "common bin/http-server lib/ test",
     "test": "vows --spec --isolate"
   },
+  "files": [
+    "lib",
+    "bin"
+  ],
   "contributors": [
     {
       "name": "Charlie Robbins",