Modifications:

  * make client connect to `PROXY_PORT` instead of `PORT`

Modifications:

  * add `PROXY_PORT` constant

Previous approach failed in case of routing table like:

    {
      'domain.com': 'localhost:9000',
      'a.domain.com': 'localhost:9001'
    }

without `hostnameOnly`. When routing request to `a.domain.com`,
`RegExp` matched first entry (`domain.com`) and returned it.

Conflicts:

	lib/node-http-proxy/http-proxy.js

Instead, just perform a request.

This handles the case where a back-end web application such as Django or
Rails issues a redirect and automatically decorates the URL with the
protocol with which it was addressed.  If the back-ends are internal and
HTTP-only, then they'll issue a URL with 'http://' as the protocol.
This must be fixed before leaving the proxy.

This also handles the (unusual) case where a back-end speaks only
https://, but the user is deploying node-http-proxy to make that service
available to non-SSL capable browsers.  Works only with 301 and 302
codes.

error-prone in-line method.

_getKey() will look for options.target as well as
options.host:options.port, and so is useful for a segmented
proxy server where the destination proxies are not constructed before
first references.

This reverts commit 30dac898.

This reverts commit 65b7872e.

if a callback but no static proxy is defined and
no routes are provided then handlers.length is 1.
However the upgrade event is still automagically
attached in spite of having an explicit callback.

[docs] grammar correction