bugfix: Eliminate error and warning messages

bugfix: Eliminate error and warning messages

Several issues have been fixed to decrease a number of warning
and error messages written to the standard output. Error and
warning messages causes false build failure report by Jenkins,
in case that internal parsing of job output is enabled.
Fixed issues:
* qemu makefile updated
* shared directories between host and guests are forcibly deleted
before vsperf execution
* nonstop_tsc cpu flag is exported from host to the guest
* vloop-vnf help has been updated and changelog added
* TCL scripts updated to print info instead of warning
* vloop-vnf image updated to avoid snmpd related warnings

Change-Id: Id9ca014bae8fa34772b67d1ebab3431682682931
JIRA: VSPERF-206
Signed-off-by: Martin Klozik <martinx.klozik@intel.com>
Reviewed-by: Maryam Tahhan <maryam.tahhan@intel.com>