proxy improvements: refactor coll selector into BaseCollSelector,
supporting either proxy auth or cookie-based selection (in progress)
https proxy: support POST requests, properly read http header and wrap remainder
in wsgi.input
https proxy: properly update wsgi for wrapped request
wbrequestresponse: add content-length 0 to redir_response
proxy_resolvers: move resolvers to seperate file, default to ProxyAuthResolver (CookieResolver still work-in-progress)