It is hard to recall a time when it was tougher to find a job. Fully two years after the official end of the recession, unemployment is at 9.2 percent. Job creation has stalled. Making things even more difficult, many employers, staffing agencies and online job-posting firms are expressly screening out applicants who are unemployed, apparently as an expedient to cull résumés, or on the presumption that the unemployed are poor performers.