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
The setCipher() function can be used to customize some options of the cipher algorithm. In the majority of the use cases it will never be used (it's set in constructor).