v0.1.5 No need to mount the binaries anymore

Some refactors and bug-fixes. The main change is container-web-tty removes the docker binary and the kubectl binary from its mounts. I used to use the "local-command exec", but this need the client binary.
I refactored it and finally removed them. The container-web-tty's size is 25M(Linux) now, most of it is kubectl's code.

BTW, kubectl's API is not user friendly. Maybe I can make a broker for it.

docker pull wrfly/container-web-tty:0.1.5