Add teams

[rubenvanerk]

The Participation model

In the Participation model is stored for which team an athlete competed in a competition.

class Participation(models.Model):
    competition = models.ForeignKey(Competition, on_delete=models.CASCADE)
    athlete = models.ForeignKey(Athlete, on_delete=models.CASCADE)
    team = models.ForeignKey(Team, on_delete=models.CASCADE)

The team name of the athlete should be displayed with the results.
A list of all participating teams should be available on the competition overview.

Team pages

A team's home page displays all club records per event per gender.
When #44 is solved, this can also be grouped by age.
On a separate page, the user can see in which competitions the team competed.
An overview of the medals won can be displayed on top of this page.
Team list should be searchable.
Teams should be able to be marked as duplicate

Misc

Team can be displayed in the Timeline
Teams can be merged, original team should become an alias for the main team.