CC-3573: Use posix_geteuid instead of "whoami" to detect who is running PHP script

-done

utils/airtime-import/airtime-import.py

@@ -18,7 +18,7 @@ logging.disable(50)
 # add ch to logger
 logger.addHandler(ch)
 
-if (commands.getoutput("whoami") != 'root'):
+if (posix_geteuid() != 0):
     print 'Must be a root user.'
     sys.exit()