Edit rescue procedure in the HTTP connection part

I am using out_http plugin in our service. it has been running in so many servers.
but, sometimes, Fluentd has been broken down(looks like freezing td-agent) because it occurred http connection error.
so, I researched this trouble, and I found it. and I edited rescue procedure in the HTTP connection part in your source.

could you please confirm my pull request?

thanks.


okay, I'll change that line after I've merged your branch.
Thanks for the patch!