VIENNA (Reuters) - Ryanair's Austrian carrier Lauda said on Friday it was closing down its Vienna base after failing to reach an agreement with unions on pay, and had already relocated many of its 15 planes to other bases.Chief Executive Michael O'Leary said earlier this month that the group would shut down Lauda's main hub in the Austrian capital and bring in Ryanair jets instead unless staff agreed to a pay cut and a new labour agreement.A Lauda spokeswoman said the shut-down involved the..