raft: rand election timeout
raft: add a test for randElectionTimeout
hack: introduce a insta-discovery script

This sets up a localhost cluster via a new discovery token. Very useful
for testing.
etcdserver: apply config change on cluster store
etcdserver: check id match
etcdserver: update panic info
etcdserver: skip bootstrap addNode entry

This is a hack to make etcd work normally.
Merge pull request #1251 from philips/hack-insta-discovery

hack: introduce a insta-discovery script
add logging and backoff and simple retry logic
Add *.test to gitignore.

These files are left by some go commands.
Raft: fix problems reported by golint.
Raft: fix printf strings found by go vet.
raft: remove misleading labels in array definition

Since these are arrays instead of maps, the "keys" here are actually
(useless) goto labels. What really matters is that the ordering is
the same between the constant declarations and the array.
etcdserver: Create, Delete -> Add, Remove
Merge pull request #1212 from unihorn/144

etcdserver: apply config change on cluster store
raft: address issues with election timeout
Merge pull request #1254 from coreos/rand_etimeout

Rand etimeout
fix retry to not retry on createSelf()
raft: save removed nodes in snapshot
Raft: a few more improvements to test messages.