fix(server/server.go): /v2/stats endpoints emit application/json content type header
server: Flush headers when using wait=true and stream=true

Many http clients will missbehave unless they get an initial http-
response, even when long-polling. It also saves the user/client from
having to handle headers on the first action of the watch, but rather
handle the response immediately.
Merge pull request #867 from iand/json-headers

fix(server/server.go): /v2/stats endpoints emit application/json content type header
etcd: add a read/write timeout to server

The default is for connections to last forever[1]. This leads to fds
leaking. I set the timeout so high by default so that watches don't have
to keep retrying but perhaps we should set it slower.

Tested on a cluster with lots of clients and it seems to have relieved
the problem.

[1] https://groups.google.com/forum/#!msg/golang-nuts/JFhGwh1q9xU/heh4J8pul3QJ
Documentation: remove etcd-py since it was removed

URL is no longer working
Merge pull request #880 from philips/add-http-server-timeouts

etcd: add a read/write timeout to server
Merge pull request #877 from Rawn/flush-headers-on-wait-stream

server: Flush headers when using wait=true and stream=true
CHANGELOG: v0.4.5
neuter osext