rusoto 0.12.1

AWS SDK for Rust
## Release trains

For pre-1.0.0:

* Targeting two releases a month for minor versions.
* Regression bug fixes will be released ASAP on best effort for maintainers.  For example, a regression in 0.9.0 means 0.9.1 is released ASAP instead of waiting for the next release train.

## Release procedure for Rusoto

### Semantic versioning

Rusoto uses [semantic versioning 2.0.0](http://semver.org/).  

### Git tags

To release version 0.4.0 of Rusoto:

1. On master, bump the version in Cargo.toml to the new version.  In this example, we'll set it to 0.4.0.
2. Commit to master.
3. Use an annotated tag on the commit with the version bump: `git tag -a v0.4.0 -m "0.4.0 release."`
4. Push changes, including tags, to Github: `git push --tags origin`.

### Crate publishing

To publish on crates.io:

1. `cargo package`
2. `cargo publish`

### Documentation

Docs are on Github Pages at [http://dualspark.github.io/rusoto/](http://dualspark.github.io/rusoto/).

A helper script is included to make this less painful until our CI system handles it.  Run `docgen.sh` to
use [github pages import](https://github.com/davisp/ghp-import) to upload them to the gh-pages branch.  Install
ghp-import if you don't have it:

`pip install ghp-import`