code: func (c *dbinitCmd) wipeMongo() error {
  	if c.dbType != "mongo" {
  		return nil
  	}
  	session, err := c.mongoSession()
  	if err != nil {
  		return err
  	}
  	defer session.Close()
  	if _, err := session.DB(c.dbName).C(mongo.CollectionName).RemoveAll(nil); err != nil {
  		return err
  	}
  	return nil
  }
docs: // wipeMongo erases all documents from the mongo collection
  // if c.dbType is "mongo".