Add proxy mode.
Proxy promotion.
Add automatic node promotion / demotion.
Add auto-demotion after peer inactivity.
Check for peer before demotion.
Fix JoinCommand comment.
Minor fixes.
feat(scripts/test-cluster): create three proxy nodes

This uses some sleep hackery to make sure that window 1 has followers
and window 2 has proxy machines. Seems to work!
Merge pull request #4 from philips/benbjohnson-proxy

feat(scripts/test-cluster): create three proxy nodes
Fix PUT /config response and log errors.
Merge branch 'proxy' of https://github.com/benbjohnson/etcd into proxy
Add /machines and /machines/:name endpoints.
Minor fixes to proxies.
Add minimum active size and promote delay.
Allow partial cluster config updates.
refactor(listener) refactor listener related code
Remove duplicate code around creating http listener.
Start to listen incoming http requests just before serving them.
Merge pull request #626 from xiangli-cmu/refactor_listener

refactor(listener) refactor listener related code
feat(Vagrantfile): Add Vagrantfile for easy start
chore(fixtures/ca): make all certificates generated by etcd-ca
Merge pull request #621 from unihorn/34

chore(fixtures/ca): make all certificates generated by etcd-ca