Remove package dependency on PHP 5.6.

Since the package itself doesn't use any language features not present in PHP 5.4, I've downgraded the composer php requirement to >=5.4.

Note that running tests for this package does require PHP >= 5.6 since I'm using phpunit 5.x.

Fix PHP version in Composer

This package requires PHPUnit 5.x, which requires PHP >= 5.6. This release updates this package's composer.json file to reflect this requirement.

Prevent casting empty values to ValueObjects.

Don't cast empty values (null or '') to value objects. Instead, return null.

Initial Release

v1.0

Initial commit.