Added a 're-resolve-destip' option

Hi there,

I added a 're-resolve-destip' option. When this option is on, the proxy server ignores the destination IP of the request, and resolve the destination IP using HOST field for http or SNI for https. 

This option is used for following situation:
* The client wants to take advantage of the proxy server's DNS.
* The client deliberately set the hosts file to proxy specific domains.
* The server redirects the request to somewhere else in conjunction with server's hosts file.