feat(docker registry): add Vagrantfile for Docker registry

Adds a contrib/docker-registry directory with a Vagrantfile that
configures and starts a VM with the Docker registry service.
chore(*): rely on etcdctl in deis/base

As of deis/base#4, etcdctl v0.4.2 includes the --no-sync option.
We no longer need to install an etcdctl branch just to get this
option.
fix(logger): turn off verbose untar'ing

untar'ing go's tarball dumps out a lot of unneeded lines. This
cleans up the build process a bit.
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
docs(contrib): fix DEIS_HOSTS example

Previous example was invalid.
chore(Makefile): clean up rsync excludes
docs(README): denote `make build` as optional

It's only necessary when making code changes.
Merge pull request #1198 from deis/readme_build_deis

docs(README): denote `make build` as optional
docs(installing_deis) add xip.io address for registering on EC2

closes #1126
docs(configure-dns): move xip.io to new section
fix(Makefile): exit until loop if service becomes failed
fix(builder): allow filesystems other than btrfs
docs(using_deis/using-buildpacks): fixing unexisting opdemand/example-ruby-sinatra git repository

Git repository opdemand/example-ruby-sinatra does not exist. Fixed it by changing it to deis/example-ruby-sinatra
Also changed opdemand/example-java-jetty to deis/example-java-jetty
Merge pull request #1200 from mvanduijker/master

docs(using_deis/using-buildpacks): fixing unexisting example example-ruby-sinatra git repository
Merge pull request #1166 from deis/logger-verbose

fix(logger): turn off verbose untar'ing
Merge pull request #1202 from deis/builder-storage-driver-opt

fix(builder): allow filesystems other than btrfs
Merge pull request #1201 from deis/exit-loop-if-failed

fix(Makefile): exit until loop if service becomes failed
Merge pull request #1163 from deis/remove-etcdctl

chore(*): rely on etcdctl in deis/base
chore(builder): rely on deis/base to manage confd

Please test this PR in conjunction with deis/base#3
Merge pull request #1161 from deis/confd-v0.4.1

chore(builder): rely on deis/base to manage confd