code: function(domain, ip, groupName) {
  		groupName = groupName || this.defaultName;
  		this._batchHost(function(hostsobject) {
  			var group = hostsobject[groupName];
  			if (group) {
  				var _group = [];
  				for (var i = 0; i < group.length; i++) {
  					var host = group[i];
  					if (host.domain === domain && host.ip === ip) continue;
  					_group.push(host);
  				}
  				if (_group.length === group.length) return false;
  				hostsobject[groupName] = _group;
  				return hostsobject;
  			}
  		});
  	}
docs: 删除一个host