LU-233 test: Remove taring of log files in gather logs.

LU-233 test: Remove taring of log files in gather logs.

gather_logs in test-framework zips the logs for no apparent purpose
just adding to the file storage. In fact it creates multiple bz2
files which contain one another. This change removes all the bz2
stuff

Change made to remove Russian dolls whilst keeping behaviour of
recovery-*-scale tests

Signed-off-by: Chris Gearing <chris@whamcloud.com>
Change-Id: I76a15a44395c0bdf4ee01e9240b64bdcdf8b25ed
Reviewed-on: http://review.whamcloud.com/1398
Tested-by: Hudson
Reviewed-by: Brian J. Murrell <brian@whamcloud.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Yu Jian <yujian@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>