feat(Makefile): move rsync from Vagrantfile to Makefile

Moves rsync from the Vagrantfile to the Makefile, enabling
development to occur on non-local Deis deployments (EC2, Rackspace,
etc.).

TESTING: ensure `make build` works the same way, both for the
main Makefile and the individual component Makefiles. To test for
a remote deployment:

```console
$ DEIS_HOSTS="54.12.21.12 54.13.11.4 55.61.2.4" make build
```

You can also test the `make rsync` target directly.

closes #1020
can we remove the first three `--exclude` options here? `htmlcov` lives in `controller/htmlcov` when you run make -C controller coverage, logs is not created (`controller/logs`), and excluding `docs` from rsync could be potentially confusing when doing development on the docs (such as the work being done at https://github.com/deis/deis/tree/docs-as-a-service).