By Catherine Hornby and Antonella Cinelli ROME (Reuters) - Italian center-right leader Silvio Berlusconi pulled his ministers out of the cabinet on Saturday, effectively bringing down the government of Prime Minister Enrico Letta and leaving the euro-zone's third-largest economy in chaos. Talks will now start to find a parliamentary majority to back a new cabinet and avoid going back to an election just seven months after the last one. ...