Bugfix: Removing pointless fastcgi_index parameter

fastcgi_index applies only if url ends with /, so it is useless for \.php$ anyway. For /, we already supply
SCRIPT_FILENAME, so it gets messy if we supply both - and breaks the APIs, since fastcgi_index would be
appended to all calls ending with /
Merge pull request #283 from fh/t/fix-api

Bugfix: Removing pointless fastcgi_index parameter