Add Docker link style env vars to link containers to services.

Add firewall instructions to the update demo

Changed the keepChannel to buffered channel.

Since the keepChannel is used to send data, not just for synchronizaiton,
so make it a buffered channel can avoid unnecessary goroutine yields.

Add some sanity checks to the kube-up script.

make build script works on os x if the current dir is not the kubernetes root

pkg/controller: cleanup replication_controller.go

Make {random,firstfit} scheduler thread safe.

Fix build script for os x.

pkg/proxy/config: clean up file.Run()

Make hack/config-go.sh sourceable from zsh

pkg/kubelet: clean up server http error handling

pkg/kubelet: explicitly return nil as error and nil as a result on error

pkg/proxy: remove unnecessary go routine

Add comments on registry/etcd_registry.go to address some of golint errors.

pkg/selector: set the cap for slice in SelectorFromSet

pkg/master: correct error string for GetPodInfo

pkg/proxy: filtering before comparing

pkg/proxy: use net.SplitHostPort instead of strings.Split

pkg/proxy: remove unnecessary io.EOF checking

Fixes go lint errors on pkg/registry/controller_registry.go