Style the repository report further

I continued to style the repository report page. Among other things, I
have removed the header tag to display the score. It is quite a bad
habit to use header tags just because they are already styled.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Rename metrics method to list

Metrics.metrics is an inaccurate name for retrieving a list of metric
symbols, hence I renamed it.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Fix all repository selection

Since I removed one layout file I had to re-provide the parameter value
again to make the link creation for the 'All' selection working again.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Write partial for dropdown menu

I have written a partial to extract the dropdown menu. This works very
well so far. I have to extend the helpers a bit more.

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