Refactor of pipeline for adding computes

This commit brings possibility to deploy additional compute into the
cloud without several reboots (for proper configuration of network
interfaces).

Key features:
  * No reboots for network configuration
  * No losing salt-minion during service restart
  * Proper step-by-step states execution
  * Fix contrail-vrouter-agent service is down at the end of highstate

Change-Id: I78c89f9d67f438046a07f366545749082ae00529
1 file changed