Revert "Add an api object for the kubelet, and a versioned endpoint."

This reverts commit d4b997938216bdf290f80127ef36145b66e75b18.
Merge pull request #2919 from brendandburns/kubelet

Revert "Add an api object for the kubelet, and a versioned endpoint."
refactor scheduler factory to use plugin architecture style like credentialprovider and cloudprovider for configuring priority functions and fit predicates.