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 see now it's part of the production deploy, which makes sense. These tests should probably be runnable as a matter of course when deploying to a new environment.