Suppress warnings from flask_sqlalchemy
    
    This patch prevents flask_sqlalchemy from printing these warnings.
    
    UserWarning: SQLALCHEMY_DATABASE_URI not set. Defaulting to
    "sqlite:///:memory:".
      'SQLALCHEMY_DATABASE_URI not set. Defaulting to '
    
    FSADeprecationWarning: SQLALCHEMY_TRACK_MODIFICATIONS adds significant
    overhead and will be disabled by default in the future.  Set it to True
    or False to suppress this warning.
      'SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and '
    
    Signed-off-by: Chenxiong Qi <cqi@redhat.com>