def unlock(path, locktoken)
     headers = {'Lock-Token' => '<'+locktoken+'>'}
     path = @uri.merge(path).path
     res = @handler.request(:unlock, path, nil, headers.merge(@headers))
    end
def unlock(path, locktoken)
     headers = {'Lock-Token' => '<'+locktoken+'>'}
     path = @uri.merge(path).path
     res = @handler.request(:unlock, path, nil, headers.merge(@headers))
    end
Send an unlock request to the server

 Example:
   dav.unlock(uri.path, "opaquelocktoken:eee47ade-09ac-626b-02f7-e354175d984e")