Do not start logging thread on stats_logging_interval == 0
Do not start logging thread on stats_logging_interval == 0

Summary: we don't respect this option and actually end up in an infinite loop :-(

Test Plan: mcrouter unit tests

Reviewed By: aap@fb.com

Subscribers: alikhtarov

FB internal diff: D1749566

Tasks: 5528304

zhlong73/mcrouter,seem-sky/mcrouter,synecdoche/mcrouter,easyfmxu/mcrouter,is00hcw/mcrouter,facebook/mcrouter,seem-sky/mcrouter,yqzhang/mcrouter,is00hcw/mcrouter,yqzhang/mcrouter,apinski-cavium/mcrouter,nvaller/mcrouter,seem-sky/mcrouter,yqzhang/mcrouter,yqzhang/mcrouter,tempbottle/mcrouter,seem-sky/mcrouter,reddit/mcrouter,nvaller/mcrouter,reddit/mcrouter,tempbottle/mcrouter,leitao/mcrouter,tempbottle/mcrouter,facebook/mcrouter,apinski-cavium/mcrouter,apinski-cavium/mcrouter,easyfmxu/mcrouter,easyfmxu/mcrouter,synecdoche/mcrouter,facebook/mcrouter,leitao/mcrouter,reddit/mcrouter,glensc/mcrouter,leitao/mcrouter,zhlong73/mcrouter,synecdoche/mcrouter,evertrue/mcrouter,reddit/mcrouter,zhlong73/mcrouter,nvaller/mcrouter,leitao/mcrouter,evertrue/mcrouter,tempbottle/mcrouter,glensc/mcrouter,nvaller/mcrouter,evertrue/mcrouter,apinski-cavium/mcrouter,facebook/mcrouter,glensc/mcrouter,is00hcw/mcrouter,zhlong73/mcrouter,glensc/mcrouter,easyfmxu/mcrouter,evertrue/mcrouter,is00hcw/mcrouter,synecdoche/mcrouter