Made some style updates
Rearranged competition detail page a little
Added 'user_registered' to CompetitionViewMixin context
Added 'on_team' to TeamDetailView context
Ditched the competition details accordion in the sidebar
Only display sidebar when user is registered
Added user_registered to CompetitionDetailView

It doesn't inherit from CompetitionViewMixin
Resize competition_detail when there's no sidebar
Don't show register button if the user is registered
Removed invitation buttons
Added user_team to CompetitionViewMixin context
Show a 'my team' button instead of 'create team' when team exists
Use competition base for team-create form
Don't allow team avatars right now

The foreign key thing isn't going to work
Use crispy forms for team create
Only show 'leave team' button if they are on a team
Rearranged team details
Added user_team to CompetitionDetailView context
Updated base template for team_leave
Fixed get_competition() parameters for several mixins