Create docker image for kubelet

[pmorie]

@vmarmol Not sure who else to tag on this one.

[pmorie]

A couple things I found about the wheezy backport used by the hypercube image:

1. Not the right version of libc required for kubelet
2. No nsenter binary even though util-linux is installed

So, I used centos for now; I'm completely open to suggestions about a better image to use.

[vmarmol]

I think we tend not to add .gitignore files :P

[vmarmol]

LGTM, nothing really a blocker.

[dchen1107]

How are we going to handle development version kubelet image?

[pmorie]

@dchen1107 For that, there's a 'local' target in the makefile. There are a ton of ways we could automate it a bit better -- any preference?

[pmorie]

Ok, I'm going to remove the gitignore file. Let's make a follow-up issue to make the image uniform with the other 'official' images. To me it would be ideal to just be able to build static binaries and dump them into a scratch image, but there are a couple packages in the kubelet that need native code.

[pmorie]

Aight, should be ready to go in, assuming everyone is cool w/ redirect to host logfile as a follow-up.

[vmarmol]

LGTM, will merge tomorrow during merge hours.