ROME (Reuters) -Italy has asked bidders willing to take over Ita Airways to come up with improved proposals, the economy minister said on Thursday, because the government does not deem the current bids to be sufficient. Neither of the two rival bids currently fully met the government’s goals for the privatisation of the company, Economy Minister Daniele Franco told a news conference. Shipping group MSC and Germany’s Lufthansa are facing a rival bid made by a consortium comprising U.S. private equity fund Certares, Air France-KLM and Delta Air Lines Inc. Lufthansa Chief Executive Carsten Spohr …