Use cfg01-day01 image for salt-master node

Add possibility to specify a separate image for cfg01 node
using environment variable IMAGE_PATH_CFG01_DAY01

If the variable wasn't set, then image from IMAGE_PATH1604 will be
used.

Change-Id: Ic8983098452f0d0486b13aba6eea15925bf03393
diff --git a/tcp_tests/templates/virtual-pike-ovs-dpdk/underlay.yaml b/tcp_tests/templates/virtual-pike-ovs-dpdk/underlay.yaml
index 1bb3c58..f341ebb 100644
--- a/tcp_tests/templates/virtual-pike-ovs-dpdk/underlay.yaml
+++ b/tcp_tests/templates/virtual-pike-ovs-dpdk/underlay.yaml
@@ -141,8 +141,11 @@
 
         group_volumes:
          - name: cloudimage1604    # This name is used for 'backing_store' option for node volumes.
-           source_image: !os_env IMAGE_PATH1604  # https://cloud-images.ubuntu.com/xenial/current/xenial-server-cloudimg-amd64-disk1.img or
-                                             # http://apt.tcpcloud.eu/images/ubuntu-16-04-x64-201608231004.qcow2
+           source_image: !os_env IMAGE_PATH1604  # https://cloud-images.ubuntu.com/xenial/current/xenial-server-cloudimg-amd64-disk1.img
+           format: qcow2
+
+         - name: cfg01_day01_image               # Pre-configured day01 image
+           source_image: {{ os_env('IMAGE_PATH_CFG01_DAY01', os_env('IMAGE_PATH1604')) }} # http://images.mirantis.com/cfg01-day01.qcow2 or fallback to IMAGE_PATH1604
            format: qcow2
 
         nodes:
@@ -158,7 +161,7 @@
               volumes:
                 - name: system
                   capacity: !os_env NODE_VOLUME_SIZE, 150
-                  backing_store: cloudimage1604
+                  backing_store: cfg01_day01_image
                   format: qcow2
                 - name: iso  # Volume with name 'iso' will be used
                              # for store image with cloud-init metadata.