client: pass around statuscode instead of Response

There's no real need for do and doWithTimeout to return Responses when
the only field of interest is the status code.

This also removes the superfluous httpMembersAPIResponse struct.
Merge pull request #1499 from bcwaldon/client_clean

client: pass around statuscode instead of Response
etcdhttp: s/TestServeAdminMembers*/TestServeMembers*/
Merge pull request #1501 from bcwaldon/rename-members-tests

etcdhttp: s/TestServeAdminMembers*/TestServeMembers*/
raft: add tests based on section 5.1 in raft paper
Merge pull request #1497 from unihorn/189

raft: add tests based on section 5.1 in raft paper
client: log incorrect HTTP resp body as string
httptypes: add MemberCreateRequest.MarshalJSON
client: use httptypes.MemberCreateRequest in member add
client: clean up style of TestMembersAPIActionList
client: test membersAPIActionRemove
store: copy Nodes correctly in NodeExtern.Clone
Merge pull request #1502 from unihorn/192

store: copy Nodes correctly in NodeExtern.Clone
doc: add a doc for data directory
Merge pull request #1504 from xiangli-cmu/admin_guide

doc: add a doc for data directory
doc: link directly to members API
Merge pull request #1500 from bcwaldon/client-tests

Add tests for client pkg
etcdctl: add -p to ls command

This is a port of coreos/etcdctl#96
etcdctl: add --sort flag to ls command

This is a port of coreos/etcdctl#102
Merge pull request #1507 from bcwaldon/doc-fix

doc: link directly to members API