Wrong behavior of Nova cluster when performing SCALE IN after attaching LB policy

[Nguyen Ngoc Hieu]

Bug description:
 - Context: When load balancer policy is attached into cluster using nova profile, perform action CLUSTER_SCALE_IN with count = {any number of nodes other than 1}.
 - Expect behavior: the number of nodes in the cluster will decrease by an amount equal to count.
 - Actual behavior: the number of nodes in the cluster always decrease by 1 node. [Bug]

Perform debug:
 - Testcase: CLUSTER_SCALE_IN with difference number of nodes, get unexpected results
 - Testcase: detach load balancer policy from cluster, CLUSTER_SCALE_IN with difference number of nodes, get normal results

Reason:
 - File: \senlin\policies\lb_policy.py
 - Class: LoadBalancingPolicy
 - Function: _get_delete_candidates

else: # action.action == consts.CLUSTER_SCALE_IN
    count = 1

Fix:

else: # action.action == consts.CLUSTER_SCALE_IN
    count = action.inputs.get('count', 1)