Ensure changes to ulimit parameters persist

There are two places where changes need to be recorded:

/etc/sysctl.conf
/etc/security/limits.conf

sysctl.conf is for setting a system wide ceiling:

# max open files (systemic limit)
fs.file-max = 65536

limits.conf is for setting a user space floor and ceiling:

/etc/security/limits.conf

Ensure both a hard limit and a soft limit are set, otherwise the setting will not become active.

For example: to set the number of files any user of the system may have open at a given time to 4096

*               soft    nofile          4092
*               hard    nofile          65536