pkt_gen: Add support for generating GENEVE frames

pkt_gen: Add support for generating GENEVE frames

Add option to generate GENEVE frames for decapsulation
tests.
IxNet 7.3X does not have a native support of GENEVE protocol. The
template, GeneveIxNetTemplate.xml_ClearText.xml, should be imported
into IxNET for this testcase to work.

Recent changes:
* Updated dependency
* Updated userguide
* Move inner frame variables & srcport/dstport to L4

Change-Id: I90f5fb256b51ae44bc1bc7983c599c9dbbffea08
JIRA: VSPERF-192
Signed-off-by: Dino Simeon Madarang <dino.simeonx.madarang@intel.com>
Reviewed-by: Maryam Tahhan <maryam.tahhan@intel.com>
Reviewed-by: Martin Klozik <martinx.klozik@intel.com>
Reviewed-by: Mark D. Gray <mark.d.gray@intel.com>
Reviewed-by: Al Morton <acmorton@att.com>
Reviewed-by: Brian Castelli <brian.castelli@spirent.com>