GET /api/activities
GET /api/activities/(int:activity_id)
GET /api/activities/(int:activity_id)/chart_data
GET /api/activities/(int:activity_id)/gpx
GET /api/records
GET /api/sports
GET /api/sports/(int:sport_id)
GET /api/stats/(int:user_id)/by_time
GET /api/users
GET /api/users/(user_id)
POST /api/activities
POST /api/activities/no_gpx
POST /api/sports
DELETE /api/activities/(int:activity_id)
DELETE /api/sports/(int:sport_id)
PATCH /api/activities/(int:activity_id)
PATCH /api/sports/(int:sport_id)