Fix: Create temp file in empty dirs for S3 log dir

Fix: Create temp file in empty dirs for S3 log dir

Since S3 buckets does not have an underlying file system to view empty
directories, an temp file has to be created when referencing the directory.
This allows empty folders to be viewed through cloudfront, without
returning a 404 error.

Create temp file in the format: "_%d%m%Y_%H%M%S", would
help with future clean or debugging.

Issue-ID: RELENG-4016
Change-Id: I0a635cd32da860deaada0ac0cc15bf1aa5fc2d4a
Signed-off-by: Anil Belur <abelur@linuxfoundation.org>