Send sighup to rsyslogd

After remove_nodes action, create mcollecte client
with execute_shell_command plugin for master node, and perform:

ssh root@#{master_ip} 'pkill -HUP rsyslogd'

Change-Id: I8ab764aaa3bceb9c08c99d5bfe08582c83e267c7
Closes-Bug: #1315382
Merge "Send sighup to rsyslogd"