Xen will produce the guest logs in a specified directory.
This scripts configures the above logging as expected
by the xapi plugin nova uses to read the logs.
In addition it ensures that any log that grows bigger
than 1MB will be truncated down to 5KB.
Ensuring the log directory is inside a loop back device
of a restricted size, and running this script every
minute using cron, will stop guests from using up
too much Dom0 disk space, and taking out the hypervisor
Part of blueprint xenapi-server-log
Change-Id: I4caa82f4d0620d924e37e3b605cf62b4d5b73570