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-mcp11-ovs/underlay--user-data-cfg01.yaml b/tcp_tests/templates/virtual-mcp11-ovs/underlay--user-data-cfg01.yaml
index a40dbaa..268db92 100644
--- a/tcp_tests/templates/virtual-mcp11-ovs/underlay--user-data-cfg01.yaml
+++ b/tcp_tests/templates/virtual-mcp11-ovs/underlay--user-data-cfg01.yaml
@@ -32,6 +32,7 @@
    - sudo resolvconf -u
 
    # Prepare network connection
+   - sudo ifdown ens3
    - sudo ifup ens3
    #- sudo route add default gw {gateway} {interface_name}