Support Downloading the Logs files from the Admin UI

The admin UI currently has this limitations:

To prevent performance issues admin logs output the last 2000 lines

But it lacks a download button two download the entire log. In our case we make use of a hosted GitLab service without direct access to the server. And those 2000 lines are filled-up within minutes. This in turn makes it hard to track down any issues raised by cutomers accessing the shared GitLab instance