return True/False from remove_job_file()

revised fix for https://github.com/ansible/ansible/issues/4795

library/system/cron

@@ -266,9 +266,10 @@ class CronTab(object):
     def remove_job_file(self):
         try:
             os.unlink(self.cron_file)
+            return True
         except OSError, e:
             # cron file does not exist
-            return
+            return False
         except:
             raise CronTabError("Unexpected error:", sys.exc_info()[0])
 
@@ -464,10 +465,7 @@ def main():
         crontab.write(backup_file)
 
     if crontab.cron_file and not do_install:
-        if crontab.remove_job_file():
-            changed = True
-        else:
-            changed = False
+        changed = crontab.remove_job_file()
         module.exit_json(changed=changed,cron_file=cron_file,state=state)
 
     job = crontab.get_cron_job(minute, hour, day, month, weekday, job, special_time)