remove thirty-two dependency

The code does not use it, if a person wants to base32 encode, they can
just install the package themselves and use it.

package.json

@@ -15,9 +15,7 @@
   "engines": {
     "node": ">= v0.4.10"
   },
-  "dependencies": {
+  "dependencies": {}
-    "thirty-two": "0.0.1"
-  },
   "devDependencies": {
     "expresso" : "0.9.0"
   }