Redesign the challenge leaderboard

Since we introduced a way for every user to create a custom exercise the old layout for the leaderboard was not displaying the most important information. So we decided that it is a time for a little upgrade.
The old leaderboard
- Lots of data
- Lots of empty space
- Horizontal scroll
- Hard to see your current position and total points
- Did not display the next rank points
The NEW leaderboard
- Displays the most important data
- Got a better use of the empty space
- Got rid of the horizontal scroll
- You can now see both the position and the total points
- A hint that shows you the required points for your next rank
As always feedback is appreciated. Let us know how we can improve from our feedback section.