v0.2.0-rc1: CAS, Tiered Config, Refactoring, Hardening

This is a release candidate for v0.2.0. We've added a lot of additional features since v0.1.0:

• Compare-and-Swap (CAS) operations are now available so you can conditional set values on keys. It's an essential component to building distributed lock systems.
• Tiered configuration allows you to specify arguments on the command line, through environment variables, or by loading a configuration file.
• Recursive GET requests can retrieve all data within a directory.
• GET requests can be fully consistent by specifying the consistent=true query parameter.
• Clients can now watch for expiring keys.
• Versioning on the internal protocol will allow you to run multiple versions of etcd in a cluster and perform rolling upgrades.

We've also dedicated a ton of resources to refactoring code and significantly improving unit tests and migration tests.

Please download the binaries and give us your feedback. If you have any trouble, just send an issue to the GitHub Issues page.