Added link for etcd-backup
raft: stop tickElection when the node is not in peer list

This prevents the bug like this:
1. a node sends join to a cluster and succeeds
2. it starts with empty peers and waits for sync, but it have not
received anything
3. election timeout passes, and it promotes itself to leader
4. it commits some log entry
5. its log conflicts with the cluster's
raft: move logic to separate func
Merge pull request #1148 from ThomasAlxDmy/master

Add link for etcd-backup
etcdserver: correct timeout and streaming handling

This reintroduces the 'stream' parameter to support long-lived watch
sessions. These sessions respect a server timeout (set to 5 minutes by
default).
etcdserver: use Context to communicate timeout, and add tests
etcdhttp: add test for streaming watches
etcd: warn on deprecated flags
Merge pull request #1138 from jonboulle/1138_timeout

etcdserver: handle watch timeouts and streaming
Merge pull request #1149 from unihorn/137

raft: stop tickElection when the node is not in peer list
scripts: consolidate and standardize protobuf generation
etcd: override flag usage func

No need to communicate deprecated flags, so prevent them from getting
printed in the usage info.
Merge pull request #1150 from bcwaldon/deprecated-flags

Slurp up deprecated flags, logging a warning
store: use nextIndex where necessary
etcdserver: extend storeRecorder to test parameters
Merge pull request #1146 from jonboulle/1146_protobuf

script protobuf generation
store: add etcd-index tests
etcdhttp: disallow empty prevValue fields
Merge pull request #1159 from jonboulle/1159_prevvalue_required

`prevValue` ignored when no value provided
etcd: correctly override flag.Usage