Expose full EOS path to users

[diocas]

To show a consistent view to the users, we should give the users access to the full EOS path. They use this path from the terminal, and will use it with the new CERNBox version as well (including from the web).
One added advantage of this approach is that users will also be able to access EOS Projects and shares of other users, without having to create the virtual folder swan_sharing_folder, as we do now.

This means that the user should start his home in /eos/user/letter/username, instead of /. This should be possible by setting the root directory to /eos and then redirect users to /eos/user/letter/username. To be seen how well this works and if we need any special configuration (that might not be implemented yet in the upstream) to force opening a special path when clicking the "home" button in Lab.