v0.1.8: Fix builds on older stable Rust

There was an unexpected build failure on Linux for 0.1.7 because it was
using an older version of Rust to make the static release binaries than
it was using to run the regular tests.

This release should restore compatibility with the older Rust we're
using to make binaries (which I also need to update).

v0.1.7: up --init, rm -fv, better status, several fixes

Third-party contributors to this release include Jeremy White, who fixed
a test suite failure on the experimetal Windows port and provided
extensive data about Docker on Windows, and Seamus Abshere who
contributed a glossary of `cage` terminology.  Thank you for your
contributions!

Bug fix:

- The `cage test` command now works correctly again, and a comprehensive
  integration test suite has been added to prevent further regressions.

New features:

- We now talk directly to the Docker daemon for several new features
  using the `boondock` library, a `cage`-specific fork of the very
  useful `rust-docker` with partial support for Docker 1.12 and Windows.
- `cage up --init` can now run task containers to initialize databases
  and other services on first run.  This has a built-in port scanner to
  make sure your containers have had time to spin up.
- The `rm` command now supports `-f` and `-v` options similar to those
  of `docker-compose`.

v0.1.6: Fix Linux releases on latest Travis setup

Docker had stopped working on our Travis builds, which meant we didn't
build any Linux binaries.  This release should fix that.

Internally, we've also fixed many, but not all, unit test failures on Windows.

v0.1.5: Fix Linux release builds

There was an issue with the automated Linux build that only triggered
when making a release.  This should fix it.

v0.1.4: Project status, building without OpenSSL, Windows experiments

- Based on an excellent suggestion from Luis Lavena, `cage new` now
  uses named volumes for the default project.  This improves performance
  and simplifies initial setup on non-Linux platforms.
- You can now use the `cage status` command to get an overview of the
  current project, including pods, services, ports and mounted source
  code.  We plan on extending this in future releases.
- You can build `cage` without OpenSSL support!  This will also disable
  Vault support.  To do this, pass `--no-default-features --features
  default-minimal` to `cargo` when installing or building.
- Thanks to heroic efforts on the part of Jeremy White, we now have
  highly experimental Windows support.  Not all the test cases are
  passing yet, and Docker development on Windows has a number of
  limitations, but we're excited to see this work on a new platform!

v0.1.3: Named volume support and initial parallelization work

We implement named volume support (see faradayio#13).  We've also converted one
internal loop to use parallelism with rayon, which should have an
imperceptible impact on performance—unless you're using the vault
plugin, which should now be faster.

v0.1.2: Tweak app created by `new` for easier tutorials

During the presentation at Boston Rust, I realized we could simplify the
"first run" experience considerably by replacing the `migrate` pod with
a `rake` pod in the app we generate.

v0.1.1: Add `logs` subcommand, and clone automatically on `mount`

v0.1.0: Breaking changes for public release

We're almost ready to talk about cage in public!

Breaking changes (we rushed a bunch of these in under the wire before
the public release to minimize breakage later):

- Rename `repo` → `source`, and `repo list` → `source ls`.
- Rename `config/libraries.yml` to `config/sources.yml` and change
  format.
- Rename `override` → `target` everywhere: `--target`, `pods/targets`,
  `enable_in_target`, etc.

Other improvements:

- Add `source mount` and `source unmount` commands.
- Automatically generate `config/secrets.yml` for new projects and
  demonstrate good secret handling.
- Allow source code for services to be part of the main repository.

Bug fixes:

- Fix bug where we mounted local library source trees even if they
  didn't exist.

v0.0.22: Pull hooks, `rm`, more flexible args, better performance

- Cage is now 20× faster!  (It was fairly fast before, now it runs in
  around 0.01 seconds on a fairly large project.)
- We now support pre-`pull` hooks in `config/hooks/pull.d`, so you can
  do things like log into ECR before pulling images.
- The `rm` subcommand can be used to remove stopped containers.
- The `build`, `pull`, `stop` and `up` commands can now take arguments
  of the form `podname`, `podname/servicename` or just `servicename` (if
  unique).