scripts: import script from 0.5 release

It isn't pretty but this was the tool used to build the zip and tar
files for 0.5
scripts: build-docker

Build docker images from the release tarballs. The default CMD is
etcd.
Merge pull request #1433 from philips/add-build-docker-script

scripts: build-docker
Merge pull request #1431 from philips/build-release-script

scripts: import script from 0.5 release
etcdserver/etcdhttp: treat /v2/admin/members and /v2/admin/members/ equally
etcdhttp: DELETE on members = MethodNotAllowed
Merge pull request #1429 from coreos/1392

Fix #1392
etcd: ensure data dir is writable

etcd checks that the data dir is writable by writing and removing an
empty file to the data dir during startup and exits non-zero if that
fails.

fixes #876
Merge pull request #1439 from kelseyhightower/check-data-dir-permissions

etcd: ensure data dir is writable
etcdhttp: make admin HTTP endpoint return json format error