replaced FollowSymlinks with SymLinksIfOwnerMatch

For security reasons, followsymlinks is disabled on some (shared) servers and leads to an Error 500. Using SymLinksIfOwnerMatches fixes that issue.

A (german) blog post why `FollowSymlinks` is disabled on [Uberspace](http://uberspace.de) can be found here: http://blog.jonaspasche.com/2014/07/11/followsymlinks-vs-symlinksifownermatch/