replace docker deployment image

now based on jessie, and not using static linking and busybox any more.
getting the tests statically linked seemed more of a hassle now that we are
on Go 1.4, and it looked hacky before.

you can still build a static cockroach binary via `make STATIC=1 build`.
Merge pull request #241 from tschottdorf/deployimg

replace docker deployment image
put path in const
fix merge conflicts