less invasive apache <Directory> config
use the new apache 2.4 access control option

https://httpd.apache.org/docs/current/upgrading.html#run-time
Merge branch 'readmesmall' into apache-config-change
updated the Linux installation part of the README

The only Option we need is FollowSymLinks (which is needed for mod_rewrite).
only expose the XBMC virtual filesystem and not the whole API when used with a proxy
updated the README with regards to proxy location configuration

The point is to from now on only proxy the /vfs location on XBMC's web server since it's the only one that has to be exposed publicly (all other API requests happen internally).
correctly mangle paths when a proxy location is specified now that we
only put the /vfs location behind a reverse proxy
add a link to the README to the proxy location field in the backend
configuration form