[Validator] Support "maxSize" given in KiB

[webmozart]

The File constraint should support the following notations for the "maxSize" option:

new File(array('maxSize' => 1234)); // bytes
new File(array('maxSize' => '2k')); // kilobytes (case insensitive)
new File(array('maxSize' => '2ki')); // kibibytes (case insensitive)
new File(array('maxSize' => '1m')); // megabytes (case insensitive)
new File(array('maxSize' => '1mi')); // mebibytes (case insensitive)

// etc.

The conversion of the passed value to the number of bytes should be done already in the constructor of File, to simplify dealing with the file constraint:

$constraint = new File(array('maxSize' => '1ki'));

assert 1024 === $constraint->maxSize;

[Tobion]

The validation message suffix should also depend on the setting.

[jderusse]

There is a lot of dupplicate code in Symfony about the convertion bytes <-> humanized :

• Component/Console/Helper/Helper.php
• Component/Finder/Comparator/NumberComparator.php
• Component/Form/Extension/Validator/Util/ServerParams.php
• Component/HttpFoundation/File/UploadedFile.php
• Component/HttpKernel/DataCollector/MemoryDataCollector.php
• Component/Validator/Constraints/FileValidator.php

I thinks, we should provide a class responsible for managing those conversions.
In which component should be located this kind of service ?

[fabpot]

The duplication was done on purpose. The only way to factor out this code would be to create a new component, but I don't think it is worth it.