bugfix: Fix failure caused by unset locale

bugfix: Fix failure caused by unset locale

In case, that VSPERF detects missing locale settings, it will
set language and encodding settings to default values specified
by configuration parameter DEFAULT_LOCALE.
Localized external commands with output parsed by VSPERF
are executed with modified locale to ensure correct VSPERF
function. Locale settings for such commands is specified
by configuration parameter DEFAULT_CMD_LOCALE.

Change-Id: If5c15115b778ce90046e390f10438b780f82695b
JIRA: VSPERF-132
Signed-off-by: Martin Klozik <martinx.klozik@intel.com>
Reviewed-by: Maryam Tahhan <maryam.tahhan@intel.com>
Reviewed-by: Al Morton <acmorton@att.com>
Reviewed-by: Brian Castelli <brian.castelli@spirent.com>
Reviewed-by: Gurpreet Singh <gurpreet.singh@spirent.com>
Reviewed-by: Tv Rao <tv.rao@freescale.com>