Get MaskBuilder from MaskBuilderRetrievalInterface

[wouterj]

This makes it easier to use a custom MaskBuilder.

continues #15

[enekochan]

Hi, I've come up to this same issue when trying to set a custom permission in the command line. I was going to do a PR with a fix but found this PR. Can this be unlocked/merged?

How would I use my own MaskBuilder after this PR is merged? My fix does not use a MaskBuilderRetrievalInterface, it only adds Symfony\Component\Security\Acl\Permission\MaskBuilder class as a service named security.acl.mask.builder, uses it in the command construct and later in execute(...) and finally in my app I replace the definition of security.acl.mask.builder class with my MaskBuilder.

Thank you!