Use local method for md5

lib/document_stores/rethinkdb.js

@@ -2,6 +2,12 @@ const crypto = require('crypto');
 const rethink = require('rethinkdbdash');
 const winston = require('winston');
 
+const md5 = (str) => {
+  const md5sum = crypto.createHash('md5');
+  md5sum.update(str);
+  return md5sum.digest('hex');
+};
+
 class RethinkDBStore {
   constructor(options) {
     this.client = rethink({
@@ -15,7 +21,7 @@ class RethinkDBStore {
   }
 
   set(key, data, callback) {
-    this.client.table('uploads').insert({ id: RethinkDBStore.md5(key), data: data }).run((error) => {
+    this.client.table('uploads').insert({ id: md5(key), data: data }).run((error) => {
       if (error) {
         callback(false);
         winston.error('failed to insert to table', error);
@@ -26,7 +32,7 @@ class RethinkDBStore {
   }
 
   get(key, callback) {
-    this.client.table('uploads').get(RethinkDBStore.md5(key)).run((error, result) => {
+    this.client.table('uploads').get(md5(key)).run((error, result) => {
       if (error || !result) {
         callback(false);
         winston.error('failed to insert to table', error);
@@ -38,8 +44,3 @@ class RethinkDBStore {
 }
 
 module.exports = RethinkDBStore;
-module.exports.md5 = (str) => {
-  const md5sum = crypto.createHash('md5');
-  md5sum.update(str);
-  return md5sum.digest('hex');
-};