refactor(makefile): remove fleet, switch to deisctl and custom images
fix(user-data): restore default discovery url
docs(readme): update root readme with new deisctl instructions
docs(hacking): new docs for hacking on deis
fix(readme): address feedback, fix typos
fix(makefile): default to 3 nodes, test for docker binary
docs(readme): add hack instructions to readme, remove newline
ref(Makefiles): use $BUILD_TAG, which defaults to "git rev-parse"
ref(tests): use images from "make build" in component tests