LU-6445 test: display test distribution accurately

LU-6445 test: display test distribution accurately

Each Linux distribution has different file and format
We will read from less common
/etc/SuSE-release for SUSE
/etc/os-release for Ubuntu, and EL6.6/EL7
/etc/system-release for EL6.5./EL6.6/EL7

Signed-off-by: Minh Diep <minh.diep@intel.com>
Change-Id: I1a4fb8418aca303ea0dbe603e58fbfa916b8e20b
Reviewed-on: http://review.whamcloud.com/14409
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>