Using Fabric Reboot operation and checking for the active CFGM node

1]. Instead of a check for the first node in the cfgm_ips list,
    check for the active cfgm node, when rebooting nodes.
2]. Instead of statically specifying sleep time, use fabric reboot
    to retry connection to a node.

Change-Id: Icba5fbe78273e8e5ebd2c59964a730362179cb53
Merge "Using Fabric Reboot operation and checking for the active CFGM node"