One my web server the users home doesn't exist, it is only
mounted from the shell machine, the web server can't see it.
Web file are instead in a different directory (which is
ln -s'd from home). This makes ~user useless.

My request? user_base this, if empty causes the
<user's home>/user_dir to be used, if not empty then when
~foo/bar is recieved, user_base/foo/user_dir/bar is used.
i.e. it's the base where user directories are to be found.

(It can also be set to /not or something like that to
essentially disable ~ since no ~ files will be found since
/not doesn't exist.)