*: move srv into pkg discovery
rafthttp: set the API boundary of the package
Merge pull request #1802 from yichengq/235

rafthttp: set the API boundary of the package
Merge pull request #1999 from xiang90/discovery_srv

*: move srv into pkg discovery
etcdserver: move getExpr to timeutil
rafthttp: transport cleanup
Merge pull request #2010 from yichengq/264

rafthttp: cleanup transport
Merge pull request #2011 from xiang90/timeutil

etcdserver: move getExpr to timeutil
etcdserver: add id generator
Merge pull request #1952 from yichengq/262

etcdserver: add id generator
etcdserver: print out log of normal tests
etcdserver: add multi_server_test.go
README.md: New etcdctl link
Merge pull request #2016 from Mic92/patch-1

README.md: New etcdctl link
etcdserver: refactor server tests

1. remove redundant fake struct
2. use fake node for better testing
3. code clean
Merge pull request #2015 from yichengq/265

etcdserver: cleanup server tests
pbutil: add getbool to pbutil
Merge pull request #2017 from xiang90/pbutil

pbutil: move getbool to pbutil
etcdserver: move error to errors.go

Both server.go and cluster.go are using defined ErrX. Move error
to errors.go
Merge pull request #2018 from xiang90/server_error

etcdserver: move error to errors.go