v0.2.0-rc1

@philips @xiangli-cmu

I force merged all of `0.2` on to `master`. Also, here's the `CHANGELOG` thus far. I listed notable additions and deferred all the bug fixes to the issues page. I marked all the v0.2.0 issues appropriately as well.

```
v0.2
* Add Compare-and-Swap (CAS) support.
* Support recursive GETs.
* Support fully consistent GETs.
* Allow clients to watch for key expiration.
* Refactor low-level data store.
* Modularize store, server and API code.
* Integrate Gorilla Web Toolkit.
* Add tiered configuration (command line args, env variables, config file).
* Add peer protocol versioning.
* Add rolling upgrade support for future versions.
* Sync key expiration across cluster.
* Significantly improve test coverage.
* Improve migration testing.
* Bug Fixes: https://github.com/coreos/etcd/issues?milestone=1&state=closed

Contributors:
* Xiang Li (@xiangli-cmu)
* Ben Johnson (@benbjohnson)
* Brandon Philips (@philips)
* Yifan (@yifan-gu)
* Rob Szumski
* Hongchao Deng (@fengjingchao)
* Kelsey Hightower (@kelseyhightower)
* Adrián (@adrianlzt)
* Antonio Terreno (@aterreno)
```