HA monitor agent

``hma`` is new agent process to detect host node failure and trigger user instance HA migration process.


Example hma.conf:
```
monitor_target {
  monitor_item("ping1", :Script, File.expand_path("script/ping_monitor.sh", Dcmgr::DCMGR_ROOT))
  monitor_item("zabbix1", :ZabbixAPI, :api_uri=>'http://localhost/zabbix/api_jsonrpc.php', :api_user=>'admin', :api_password=>'zabbix', :trigger_name=>'dddd')

  conditions {
    last_ntimes_failure(5, "zabbix1")
  }
}
```