build a static cockroach binary

edit: latest update at the bottom.


* added a `make build_static`
* vendored in everything that was left: bz2, zlib, protobuf
* build only static libs
* light brushing up of the Dockerfile

next up: a small Cockroach deploy image, built after successful tests through CircleCI.
I don't think it would be a security problem (can you elaborate?). The way it works right now is that we run the static tests inside of the deploy container once after the build, but we don't actually add them to the container. So they're right now technically part of testing the deploy image, not part of testing the actual deploy.
The reason for that is is that the test binaries are huge and would increase the container size by a significant factor. We can however of course build a deploy-test image that has the tests wrapped up inside. That's however not what you'd wanna use for your everyday deploys.