By Tim Hepher and David Shepardson FARNBOROUGH, England (Reuters) – Boeing has been cranking out order announcements at this week’s Farnborough Airshow, restoring momentum to its troubled 737 MAX, while rival Airbus on Wednesday added to its A320neo order book. Boeing has secured over 100 firm orders for the MAX as it still faces big challenges to certify a crucial new variant before a year-end deadline. Qatar Airways also might be open to reviving a tentative deal for 25 MAX which had lapsed, sources told Reuters. “It’s a quiet show, but within that I think Boeing’s mojo is back,” said Agency…