Badges and achievements

[TomNaessens]

People like to show of things they've done and contests they won. I think we should implement two things here:

• Achievements: Achievements are basic things everyone can gather at all time. Such as "Generous commiter: Made 10 commits"
• Badges: Badges should display contests or prices people have won. One badge should only belong to one person. An example can be: "Top coder March 2015", "Gandalf top commiter", ... They should be passable too; for example when someone else gains the top Gandalf commits.

This probably is some work and would also require some visual things (nice graphics), but I think this would benefit contributions a lot.

[TomNaessens]

Badges could be partially automated; but they should also be easy to add for small "contests" (during an unplanned evening for example)

[iasoon]

Dependent on #66 .