permissions: flush permissions correctly for forks/repos when celery is used.

authentication: introduce login restriction option for builtin rhodecode plugin.

auth: login/registration changes for upcomming new rules for login using external identities. - show session expiration

permissions: show user group count in permissions summary, and unified some text labels.

permissions: flush default user permissions on global app permission changes.

permissions: handle more cases for invalidating permission caches - invalidate user permissions on chaning the global permissions - invalidate all users in case of creating new object with "copy permissions" flag - invalidate all users permissions in case of repo/repo group renames - invalidate all user permissions in forked repo with copy flag

repositories: handle vcs backend unavailable correctly in advanced settings.

users-admin: call changed Admin to Super admin as new notation is this one.

templates: UX, moved repo group select next to the name as it's very relavant to each other.

js: fixed some JS syntax.