Support for non-default port numbers

[root]

For example, current port forwarding test in-proxy is at x.x.x.x:1443. This breaks a few things:

            * e.php user-coming-from-expected-in-proxy-address test is broken because of the port number
            * generated invite links need to be hand edited to add 1443
            * some internal links such as click-here-to-browse after create account don't work

            Some of these issues could be patched, but it probably makes sense to add comprehensive support for non-default port numbers. Add a port number field to the proxy table, reference it where required (like, when creating an invite like) and so on.