Use os.path.join instead of hardcoded formatting

Signed-off-by: Peter Portante <peter.portante@redhat.com>
Add parameter to add_copy_spec_limit() to control tail behavior

Allow callers of add_copy_spec_limit() to disable collection of
the tail of a file when the limit is reached. This is not useful
for most binary data formats and even many text formats.

Based on a patch from Peter Portante <peter.portante@redhat.com>.

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
Handle compressed sar binary data files better

We now collect all compressed and uncompressed sar?? and sa?? data
files. Given that tailing the text output is not very useful, we add an
option to not perform the tail when we have reached the limit.

NOTES:

  * The 20 MB limit applies to each *set* of files being collected, so
    there there is a 20 MB limit for the total number of sa??* files and
    _separate_ 20 MB limit for sar??* files collected

  * The 20 MB limit *does not apply* to the generated command output, so
    if there is a 200+ MB sa?? data file present, that file won't be
    collected, but the resulting 200+ MB sar?? and sar??.xml files will
    still be collected in full

  * The generated command output for missing sar files is only generated
    from uncompressed binary data files

  * The generated command output for the XML files is also only
    generated from uncompressed binary data files

Signed-off-by: Peter Portante <peter.portante@redhat.com>
Signed-off-by: Bryn M. Reeves <bmr@redhat.com>