Moved some config options from httpd to chttpd

[jiahuili430]

Overview

Solved conflicts from "cherry-pick" 3.x commit with kdiff3 merge tool.

Testing recommendations

make eunit apps=chttpd suites=chttpd_util_test

Related Issues or Pull Requests

This fixes #3472

Checklist

• Code is written and works correctly
• Changes are covered by tests
• Any new configurable parameters are documented in rel/overlay/etc/default.ini
• A PR for documentation changes has been made in https://github.com/apache/couchdb-documentation

[tonysun83]

Based on my reading of the code, we have 3 scenarios:

1. If both chttpd and httpd config values exist, chttpd takes priority.
2. If chttpd does not exist, but old httpd value exists, then we use httpd value
3. If neither exists, we take in the passed default.

If this is the logic then it LGTM, and +1

[nickva]

+1