mod_rewrite final cleanup

Follow up for commit 34bdd032c191b503520f9cce8e4d64803031c3fe
Added compatibility for nginx (no need in any mod_rewrite and try_files)
'rrd.php/value'  is incorrect for nginx (php-fpm). 
Because by default nginx will not pass 'value' to script 'rrd.php', but will try to find file 'value' in 'rrd.php' folder.
Solves issue #11