Use custom column for identifying in methods like hasRole

[Kazuto]

Hey guys,

Many things can be configured in config/permission.php. It would be great to be able to choose the identifier for methods like hasRole as well so that we can use the standard name column or a custom column e.g slug.

I prefer having proper text in the name column like Shareholder, Developer or Super Administrator and have another unique column called slug for identification which would result in shareholder, developer, and super-administrator.
Being only able to use the name column kinda restricts the casing of names as role:Super Admininstrator just looks wrong in code and role:super-administrator would fit much better, but then super-administrator would look wrong in UI.

[PaolaRuby]

You could make a PR for that, because surely no one else is going to do