Working deploy for controller and compute nodes

- use 'dash' branch for mk-lab-salt-model repo (it has a lot of
  improvements and fixes)
- use less number of nodes to match the 'mk22-lab-advanced' model
- force update packages before configuring salt.minions
- use saltstack repo for latest salt.minions on trusty

* Note if the deploy starts from an 'underlay' snapshot,
  keepalived can lose VIP after update DHCP leases on nodes.
  It's better to start deploy from clean environment.
diff --git a/tcp_tests/templates/tcpcloud--user-data.yaml b/tcp_tests/templates/tcpcloud--user-data.yaml
index d60a87a..ecde655 100644
--- a/tcp_tests/templates/tcpcloud--user-data.yaml
+++ b/tcp_tests/templates/tcpcloud--user-data.yaml
@@ -41,6 +41,9 @@
 
    - echo "deb [arch=amd64] http://apt.tcpcloud.eu/nightly/ trusty main security extra tcp tcp-salt" > /etc/apt/sources.list
    - wget -O - http://apt.tcpcloud.eu/public.gpg | apt-key add -
+   # saltstack repo is for minions that have the same version in the xenial and trusty (2016.3.3)
+   - echo "deb http://repo.saltstack.com/apt/ubuntu/14.04/amd64/latest trusty main" > /etc/apt/sources.list.d/saltstack.list
+   - wget -O - https://repo.saltstack.com/apt/ubuntu/14.04/amd64/latest/SALTSTACK-GPG-KEY.pub | apt-key add -
 
    - apt-get clean
    - apt-get update