housecleaning

I'm cleaning house. Please help me audit this list of what is left. /cc @xiangli-cmu @unihorn 

- [x] third_party/.../go-log -> go-systemd && third_party//bitbucket.org/kardianos/osext
- [ ] third_party/.../go-etcd -- xiang is working on it!
- [ ] error/ -> ./discovery -- xiang is working on it!
- [x] http/ -- needs review (does CORS stuff in for main)
- [x] bench/ -- needs review
- [x] fixtures/ -- needs review
- [x] config/ -- we should be able to move this into etcd/
- [x] pkg/ -- needs review? what is