teach store.Store about CompareAndDelete
track CompareAndDelete stats
add compareAndDelete event action
add the CompareAndDelete command
support CreateAndDelete through the v2 server
keep the Delete tests together
implement recursive for CompareAndDelete in the store
update the v2 server to support recursive on CompareAndDelete events
mod/leader
feat(README): add notes about in-order key creation
feat(README): document the etcd request headers
Merge branch 'master' of https://github.com/coreos/etcd into mod-leader
Add leader module to README.
feat(README): add directory tutorial
Merge pull request #401 from philips/add-dir-docs

feat(README): add notes about in-order key creation
feat(README): add cetcd
Merge pull request #404 from philips/add-cetcd

feat(README): add cetcd
Merge pull request #402 from philips/add-header-docs

feat(README): document the etcd request headers
Merge pull request #398 from benbjohnson/mod-leader

mod/leader
Add Tuning section to README.