Adds bcrypt native binding for better login performance (#2549)

* Adds bcrypt native binding for better login performance

* Swaps bcrypt-nodejs for bcryptjs as compatible with bcrypt native

* Fixes package versions

src/password.js

@@ -1,11 +1,15 @@
 // Tools for encrypting and decrypting passwords.
 // Basically promise-friendly wrappers for bcrypt.
-var bcrypt = require('bcrypt-nodejs');
+var bcrypt = require('bcryptjs');
+
+try {
+  bcrypt = require('bcrypt');
+} catch(e) {}
 
 // Returns a promise for a hashed password string.
 function hash(password) {
   return new Promise(function(fulfill, reject) {
-    bcrypt.hash(password, null, null, function(err, hashedPassword) {
+    bcrypt.hash(password, 10, function(err, hashedPassword) {
       if (err) {
         reject(err);
       } else {