Migrate to new Box version for bundling

[allejo]

We need to migrate to the latest version of Box now forked and maintained by humbug, https://github.com/humbug/box

[allejo]

This will likely need to wait until I can bump the minimum PHP version of this project to 7.1 so I can start using doctrine/rst-parser because right now, our current RST parser breaks the new box bundling