Add master_ip to engine parameter section

master_ip should be passed for every task where rebooting is involved
therefore it is convenient to place them in engine section

Sending kill -HUP to rsyslogd required after removing nodes
to refresh its configuration

Change-Id: Ibd3882621380da1d5fcdb15397438f554b3619c7
Related-Bug: #1315382
Merge "Add master_ip to engine parameter section"