1. ScalingPolicy's CoolingTime will limit ScalingPolicy with 'alarm' TriggerType
2. Health Check will remove instance that has been shut down for 3 minutes.
3. If TargetNumer > SG.MaxInstanceNumber or TargetNumber < SG.MinInstanceNumber,
ScalingActivity's status will be set to 'part_success'.
4. When you want to increase the DesireInstanceNumber that has reached the maximum value,
or decrease the this that has reached the minimum value, the ScalingActivity is rejected.
5. ScalingPolicy.PostCreate and PostDelete asynchronous execution.
Feature:
1. Add apis: list server by group, list group by server, bind
servers, unbind servers, bind groups, unbind groups.
2. Add climc command and docs corresponding to the above newly added apis
3. Add log about binding and unbinding operator.
4. Support enable and disable instance group.
Fix:
1. Set capacity zeor if there are not enough resource aboue forced
instance group in one host.
2. Change the stage(real delete => pending delete) that guest leave all groups.
