Fix typo in sample config
Merge branch 'master' of https://github.com/zellux/cow into develop

Conflicts:
	doc/sample-config/rc
Add httpParent option. Try parent connection in the order specified in config.
Update sample rc, change socks to socksParent.
Support parent http proxy.
Merge branch 'feature/parent-http-proxy' into develop
Remove TODO: parse keep-alive. It's done.