Standardize directory for multi user application specific data

[Jeff Johnson]

/srv so far fits the bill perfectly but the issue is in current FHS the distro
has no control over how /srv is structured leading to many (all?) distros not
using /srv for things such as www, mail, etc this leads to what see today with
/var/www /var/mail /var/$application which is an issue for selinux and for
administration in general.
I propose either /srv is allowed to be defined by the distro or /var/srv.