Update of VPP_STABLE_VER and DPDK_STABLE_VER files

- use new vpp ref build - ubuntu 16.04:
  17.10-rc2~12-gc47652c~b42_amd64

- use new vpp ref build - centos7:
  17.10-rc2~12_gc47652c~b42.x86_64

- use new dpdk version:
  17.08-vpp2

They are needed to successfully run IPSec perf tests.

Change-Id: I3207b711404625d742c745932968e2eb68a76baf
Signed-off-by: Jan Gelety <jgelety@cisco.com>