Added the file encryption/decryption to Zend\Crypt

This PR replace the https://github.com/zendframework/zf2/pull/6410 with a new `FileCipher` implementation based on the suggestion of #6410. I removed the fluent interface and other methods not really relevant for the usage of this component. I also improved the unit tests adding the one for `Zend\Crypt\Symmetric\Padding\NoPadding`.
I also provided the documentation for this new component in this PR https://github.com/zendframework/zf2-documentation/pull/1311
should the number of iterations be protected against big values, to prevent security issues like symfony2 had in the past?
http://symfony.com/blog/security-releases-cve-2013-5958-symfony-2-0-25-2-1-13-2-2-9-and-2-3-6-released