branch-permissions: fixed override of default permissions for branches from admin page

branch-permissions: added missing ee feature screenshot for admin page

configurations: update attached configuration INI files with the ENV_ substitution infomation. In addition show better error message if substitution cannot be made.

exception-tracker: add show-more link.

branch-permissions: handle cases for revoking regular permissions when branch permissions are set: - DB cascade delete fliushing branch when repository is deleted - forbid lowering permissions if it's used for branch

ce: added example branch permissions screen for CE pages

branch-permissions: enabled branch permissions checks for SSH backend.

pull-requests: add merge validation to prevent merges to protected branches.

permissions: unified looks and buttons on permission pages. - new quick menu for some super-admin actions. e.g show permissions link

branch-permissions: handle vcs operations and branch permissions. - use new exceptions for branch permissions - detect if we need to check permissions - calculate super-admin the same way as regular users for override capabilities - added new tests for branch permissions