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

Incorrect changed result in cron module.
Report changed=False if no cron is removed:wq

system/cron

@@ -464,8 +464,10 @@ def main():
         crontab.write(backup_file)
 
     if crontab.cron_file and not do_install:
-        crontab.remove_job_file()
-        changed = True
+        if crontab.remove_job_file():
+            changed = True
+        else:
+            changed = False
         module.exit_json(changed=changed,cron_file=cron_file,state=state)
 
     job = crontab.get_cron_job(minute, hour, day, month, weekday, job, special_time)