Add new functions to logfile.go for rotating and truncating
the events log file once the log file and its contents
exceed the maximum size limit while keeping 50% of the
log file's content
Also add tests to verify log rotation and truncation
Signed-off-by: Niall Crowe <nicrowe@redhat.com>
Signed-off-by: Valentin Rothberg <vrothberg@redhat.com>