Merge branch 'vlogger' into 'master'

vlogger for more precise stats with %O for apache >=2.5

this provides a more accurate traffic statistic, since also includes the amount of bytes received according to [apache doc](https://httpd.apache.org/docs/trunk/mod/mod_logio.html)

i could not make work version >= 2.4.7, so i opted to use this for version >= 2.5

See merge request !571