Add basic config.
Add tiered configuration.
Merge branch '0.2' of https://github.com/coreos/etcd into config
Merge branch '0.2' of https://github.com/coreos/etcd into 0.2
Fix conf extension and documentation.
Merge branch '0.2' into config

Conflicts:
	Documentation/external-documentation.md
	server/config.go
	server/config_test.go
	server/tls_info.go
	server/util.go
Merge pull request #266 from benbjohnson/config

Tiered Configuration