code: func InitModels() {
  	index := mgo.Index{
  		Key:      []string{"username"},
  		Unique:   true,
  		DropDups: true,
  	}
  
  	db.EnsureIndex(mongoUsersCollectionName, index)
  
  	// Removes users without valid 2 factor authentication after 3 days
  	automaticUserExpiration := mgo.Index{
  		Key:         []string{"expire"},
  		ExpireAfter: time.Second * 3600 * 24 * 3,
  		Background:  true,
  	}
  	db.EnsureIndex(mongoUsersCollectionName, automaticUserExpiration)
  
  	avatarIndex := mgo.Index{
  		Key:      []string{"hash"},
  		Unique:   true,
  		DropDups: true,
  	}
  	db.EnsureIndex(mongoAvatarFileCollectionName, avatarIndex)
  
  	emailIndex := mgo.Index{
  		Key: []string{"emailaddresses.emailaddress"},
  	}
  	db.EnsureIndex(mongoUsersCollectionName, emailIndex)
  }
docs: //InitModels initialize models in mongo, if required.