enforce a configurable minimum password length when registering

www/common/credential.js

@@ -5,6 +5,13 @@ define([
     var Cred = {};
     var Scrypt = window.scrypt;
 
+    Cred.MINIMUM_PASSWORD_LENGTH = typeof(AppConfig.minimum_password_length) === 'number'?
+        AppConfig.minimum_password_length: 8;
+
+    Cred.isLongEnoughPassword = function (passwd) {
+        return passwd.length >= Cred.MINIMUM_PASSWORD_LENGTH;
+    };
+
     var isString = Cred.isString = function (x) {
         return typeof(x) === 'string';
     };