Add styling to repository leaderboard

Just added some basic styling to the leaderboard, removing the use of
the metric abbreviations.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Remove deprecated metric identifiers constant

Still lingering in the code are constants like metric identifiers,
metric abbreviations and metric normalizations. Two of them were
removed now. I had to adjust some code including the concerns.

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