Backports for 0.9.1

This PR backports the following PRs to 0.9 for 0.9.1:
https://github.com/dotcloud/docker/pull/4387
https://github.com/dotcloud/docker/pull/4633
https://github.com/dotcloud/docker/pull/4731
https://github.com/dotcloud/docker/pull/4648
https://github.com/dotcloud/docker/pull/4684

PR #4684 is currently making a test fail:
```
--- FAIL: TestCreateStartRestartStopStartKillRm (15.45 seconds)
        server_test.go:450: Cannot stop container 45f8a6d8e02168ca4afe43877e5f80979a3eab1924042fe737707a11b736c8e8: Timed Out
```