task.internal.archive: gzip archived file size > 128MB

task.internal.archive: gzip archived file size > 128MB

* misc: add an optional write_to argument to misc.pull_directory()
        so the caller can optionally specify the function to write
        to local file.
* task/internal: add a global option "log-compress-min-size" which
        defaults to "128MB". if the size of a file pulled from remote
        host is greater or equal to the specified size, it will be
        compressed with gzip with the extension of ".gz" before
        stored in the archive directory.

Signed-off-by: Kefu Chai <kchai@redhat.com>