Merge pull request #2 from xiangli-cmu/master

Add testAndSet Command
Merge pull request #3 from xiangli-cmu/master

clean up tree.go
Merge pull request #4 from xiangli-cmu/master

add [etcd] as the prefix of the logging info
Merge pull request #5 from xiangli-cmu/master

clean up tree.go and watcher.go
Merge pull request #6 from xiangli-cmu/master

clean command.go
some defaults
remove unneeded usage
Merge pull request #7 from polvi/master

Add some defaults.
clean up transporter.go
merge