Add AllRolesVocabulary

I am adding this new vocabulary as a result of a feedback given by @jensens for the pull request of plone.app.querystring
https://github.com/plone/plone.app.querystring/pull/20
There I've added a Show Inactive operation which allows the setting of show_inactive parameter given to the catalog for the selected Roles, and Anonymous does not show up in the original Roles Catalog.