Local (DMZ) URL for gogs workers (such as ssh update) accessing web service. In
most cases you do not need to change default http://localhost:HTTP_PORT/. You
may need to alter it only if your ssh server node is not the same as http node,
eg. running behind proxy on different node than web server.

                     --- 80 public port -> 8080 -- web server node
                    /
    public proxy --<
                    \
                     --- 22 public port -> 10022 -- ssh server node

This option is not intended to be accessible via web GUI settings, since it is
unlikely someone needs to change it to somethings else than default
http://localhost:HTTP_PORT/ which should work for most of the cases.

But this should land into the documentation somewhere.

fixup

This is the old naming of the variable and I forgot to fix it. It now
works and is tested.

This allows the admin to disable the version information about gogs and
go in use in the footer.

This moves the minimum key sizes into the config file, so that anyone
can modify the restrictions.

The same logic was duplicated in three places. Factor it
out so that we can add further fallbacks in a single place.