LA Times: Robert Knight was about to install wireless transmitters on eight new drilling rigs joining the thousands that dot the ravines and mesas here when he got the startling news: All but one of the rigs were coming down. Falling natural gas prices had led energy firms to abruptly curtail their work here last month, battering the last sector of the U.S. economy that had prospered despite the recession. “Boy, it was quick,” said Knight, who has a business installing communication …