[security] introduce sensitive value object.

[makasim]

it fixes #78

The workflow:

<?php

$model['cardNumber'] = new SensitiveValue('1111222233334444');

serialize($model['cardNumber']);
//NULL

clone $model['cardNumber'];
// exception

$model['cardNumber']->erase();
// remove value forever.

$model['cardNumber']->get();
// get sensitive value and erase it

$model['cardNumber']->peek();
// get sensitive value but not erase it. use carefully

(string) $model['cardNumber'];
// empty string

// later in action:

$model = ArrayObject::ensureArrayObject($model);
$api->purchase($model->toUnsafeArray());

//the array contains unsafe credit card number. This primitive array never stored anywhere, just passed as is to gateway.

TODO:

• add test for __clone
• add test for ArrayObject::toUnsafeArray()
• update all currently supported payment to use this object.
• update docs
• update payum rest
• update zend module
• update yii extension

[makasim]

@mtudor just added some more tests. Here you could look at real life examples:

• [security] use SensitiveValue to safely process card number etc. AuthorizeNetAim#5
• [security] wrapp authorize.net sensitive values. makasim/PayumBundleSandbox#29

working on example for symfony bundle and sandbox

[cordoval]

it would not save not saved

[cordoval]

or it would not be saved