[WIP] new: use username in metrics request url

For that we introduced a current-user namespace to handle the globally
accessibly thread-bound current-user information.
[WIP] change: remove "in progress" label from dashboard page
refactor: move calls to with-lang-from-metadata to representation ns
new: add breadcrumbs to dashboard page
fix: breadcrumbs test
[WIP] new: implement configuration page