Merge go/autoscaler into go/controller.

[helinwang]

The reason for separating them into two packages are:

go/controller contains the details about k8s cluster management system, in the future we could have other cluster management systems, and we can add it without changing the go/autoscaler package.

But currently we probably don't need to separate them because:

1. Currently we don't need to support cluster management system other than k8s
2. The go/autoscaler package are supposed to not depend on go/controller package, since it's higher level policy, and go/controller is just a cluster management system detail. But we did not do a good job, and go/autoscaler already depends on k8s detail (the resource definition are from k8s).

[typhoonzero]

So are we going to separate these two parts later?

[gongweibao]

How long does the later mean?^_^

[helinwang]

@typhoonzero I think not planned, since we don't have any plan for supporting autoscaling on anything other than k8s.

[typhoonzero]

Agree, Indeed.