Generate URLs for entity picker beforehand

I have changed the routine to generate the links for the entity picker.
By generating them in a loop it is easier to throw out illegal links
that do not map to a repository-snapshot pair.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Add routes for a future session feature

As I want to implement session to enable users with administration
rights I have added the appropriate line to the route file.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Style range input slider

Just added some custom styling for the range input sliders.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Add navigation buttons for snapshots and metrics

I have added more buttons to the navigation bar. The snapshots and
metrics button redirects to the first possible resource pair. Also
done some further styling.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>