Validation

[koria]

Problem with ImageContentValidator #5

            $imageProperties = @getimagesizefromstring($fileContent);
            if (empty($imageProperties)) {
                throw new InputException(new Phrase('The image content must be valid base64 encoded data.'));
            }
            $sourceMimeType = $imageProperties['mime'];

getimagesizefromstring () returns null for .svg images
just wrap this method with the isSvg () method and we can load .svg images via the API

Need more refactor, but now it works without problems