Record a WFS action as finished in the state.
@param {Object} state Current state.
@param {Object} action Action to handle.

@returns {Object} The new state.
function finishedAction(state, action) {
  const new_actions = Object.assign({}, state.actions);
  delete new_actions[action.id];
  return Object.assign({}, state, {actions: new_actions});
}