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
Added the ability to specify heartbeat and election timeouts as
config parameters.
Fixed test case
fix(Dockerfile): reverted unneeded changes
fix(server/config.go): ensured params are changeable from config file and env
fix(server/server.go): removed unnecessary debug line
fix(server/timeout.go): removed a commented block
style(server/transporter.go): put explicit vars to replace timeout expressions
style(tests/server_utils.go): ran gofmt to clean up indenting
feat add dir_flag
refactor(update) more clear dir checking
tests fix all tests
refactor(error.go) error messages
docs(delete_command.go) document about recursive implies dir
test fix tests
tests add tests for dir flag
refactor remove unused const
Merge remote-tracking branch 'upstream/master' into feature-parametric-timeout

Conflicts:
	Dockerfile
	server/usage.go
	tests/server_utils.go