Removed dead code

At least I hope it's dead; if it's not, we'll soon find out.
Permissions: configuration back-end
Storage/data model for user roles
Hook up Permissions with provider infra
Some role-based functionality
Renamed permissions (drop can_ prefix)
Example roles and a crude roles overview page in backend
Content-type permission checks in admin main menu
WIP apply new permissions to access control
Added used templates to Profiler

Based on a port of the Twig profiler which is part of
https://github.com/Elao/WebProfilerExtraBundle All credits to the
author of this package.
Fixed "useredit" permission checks
Fixed most path-based permission checks
Do not show "prefill database" button if lacking permission
Added extensive explanations to the default permissions file
Fixed login error
Fixed: permission handling for editcontent
End-to-end tests pass for various permissions
Added missing permissions
Fixed rebase bug
Make some functional tests pass