Restructure the repo for each scheduler extender to have its own main.go

[wangchen615]

Different schedulers work with their own annotator or monitoring agent + etcd.
Restructure the repo to :

1. Each scheduler extender has its own subfolder and main.go.
2. Each subfolder includes all necessary code to run that scheduler independently.
3. A README.md and manifests folder of yamls/scripts to run multiple scheduler-extenders at the same time.
4. Each subfolder has its own README.md for motivation of its scheduler-extender and demo steps.
5. Change the package management tool to dep and remove vendor folders.