gitignore: Ignore non vsperf files

gitignore: Ignore non vsperf files

.gitignore was updated to ignore following files:
* VPP project directory
* l2fwd binary files
* tags

JIRA: VSPERF-529

Change-Id: Idc10eae7b14c72a863f3473e02cbdc7c47d31b41
Signed-off-by: Cian Ferriter <cian.ferriter@intel.com>
Reviewed-by: Martin Klozik <martinx.klozik@intel.com>
Reviewed-by: Al Morton <acmorton@att.com>
Reviewed-by: Christian Trautman <ctrautma@redhat.com>
Reviewed-by: Sridhar Rao <sridhar.rao@spirent.com>
Reviewed-by: Trevor Cooper <trevor.cooper@intel.com>