Fix $compress_offline and /var/tmp as temp dir

$compress_offline is defined as boolean, however its default value
was a string, causing if to be always evaluated to true when
checked later.

Also, is file_upload_temp_dir is /var/tmp, we should apply the
same logic used with /tmp and not modify its owner or permissions.

Change-Id: I55cd0a2e0ebc5d23d3f43a2c87138cffd2f64253